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An alpha prototype build of Contra 4 was leaked to the public very shortly after the North American release. The prototype is dated June 27, 2007 and states to be a build of a European version. Despite containing a USA-based internal serial code, many factors support it being for Europe. This makes it an unreleased regional prototype.

2 other builds are known to exist: one from July 11th and one from August 27th. On a related note, the DS Download Station demo appears to use more prototype code than final release code.

Although the prototype’s ROM image has long been available on the internet, the prototype flash cards had been sold a few times among prototype collectors. One of the 2 known copies was exchanged from an unknown collector to the user mb7241 of NintendoAge, to DreamTR, and is now in the hands of user Jaxsbox, also of NintendoAge:


The second known copy was sold by the user mathn on NintendoAge to JaxsBox:


Most of the final version’s content is present, but there are significant differences. The levels generally vary from the final, with some being drastically different or incomplete; music and several sound effects are absent; Challenge Mode is incomplete; the intro sequence is in storyboard format (mostly colorless images) and the ending is absent. The central hub of the prototype is a Debug Menu, from which the player can access many parts of the game. Here are a few exhibits:

The game is referred to simply as Contra in the boot menu:


The debug menu:

Final boss battle, very incomplete:

The eyeballs serve a functional purpose, shooting projectiles in a sinusoidal trajectory. In addition, the 3 heads won’t lower into the screen until the eyeballs are destroyed.

The following is a list of all the selections from the Debug Menu, listed in order from the starting option:

Level Jungle: Starts the player on the Jungle stage, sometimes after having landed in the water.

Game Menu: Starts the boot sequence as the final version would (see below).

Demo Menu: Shows the Demo and Coming Soon screens from the DS Download Station demo, in a loop (see here). The game must be reset to exit this loop.

Level Waterfall: Starts the player on the Laboratory (Waterfall) stage.

Level Tunnel 1: Starts the player on the Base stage.

Level Missile: Starts the player on the Harbor stage.

– Guardian 1: Starts the player on the Harbor stage, at the Missile Hugger 3000 mini-boss battle. The player is placed in mid-air when the stage begins and they must grapple to the rail above or immediately lose a life.

– Nose Cone Separation: Starts the player on the Harbor stage, immediately after the Missile Hugger 3000 mini-boss battle.

– Boosters: Starts the player on the Harbor stage, at the missile booster flame gauntlet sequence.

– Guardian 2: Starts the player on the Harbor stage, immediately after the missile crashes.

Level Ocean: Starts the player on the Ocean stage.

Level Tunnel 2: Starts the player on the Factory stage.

Level City: Starts the player on the City stage.

– Arachnid: Starts the player on the City stage, immediately before the robotic arachnid mini-boss.

– Larvae: Starts the player on the City stage, immediately before the stage boss.

Level Tunnel 3: Starts the player on the Alien Hive stage.

Level Black Viper: Starts the player on the Harvest Yard stage.

– Post Orifice: Starts the player on the Harvest Yard stage, at the top of the climb through Black Viper’s posterior segment.

– Crushing Layer: Starts the player on the Harvest Yard stage, at the base of the climb before the series of crushing ceilings.

– Throat: Starts the player on the Harvest Yard stage, at the base of the final climb before the shutting bone slits.

– Cerebrum (Gym): Sends the player to a debug-like stage (see below).

Wireless Menu: Takes the player to the Wireless Debug Menu (see below).

Rotating Layers: Displays a plain, magenta screen with the main menu’s background layer graphic. The player can scroll, rotate and zoom in/out of the overlay.


Sound Test: Takes the player to the Sound Test menu from the Bonus Features menu (see below).

The following transcribes the text around the perimeter of the screen in the Debug Menu:

Top Left
.: welcome to contra :.

Top Right
release build
June 27 2007

Bottom Left
::: X of 24 ::: *

bottom right

*Where X is the current menu option highlighted, starting with Level Jungle.

General Information

-This build is highly unstable. Crashes can occur at any given time, even from selecting options on the Debug Menu. These crashes range from a black screen to various memory error messages on a blue screen, as shown below:


-Frequent general bugs and glitches, such as glitched enemy spawning and behavior, random deaths, disappearing elements, etc.

-All stage selections from the Debug Menu starts the player as Bill Rizer, with the Normal Gun and 99 lives and on the Normal difficulty setting. The game also starts the stage immediately when accessed through this menu, instead of first displaying the intermission sequence. The lives are reset to 99 upon progressing to the next level.

-Numerous sound effects are missing. Notable examples include all voice clips, grapple sound during gameplay and all boss destruction sound effects. Several sound effects from the final do not play anywhere in the prototype, except for in the sound test in some cases (either due to not being implemented to any capacity or its location in the game being inaccessible by simple means).

-Although music is present in the ROM, none are played in-game. Every included music track (see here) differs to some degree. The Laboratory stage’s starting area uses a completely different tune; the waterfall section of the Laboratory, Base (Tunnel 1) and Ocean stages’ tracks are considerably different; the music track for the Harbor (Missile) stage is likely corrupted. While the rest of the tracks differ to a lesser degree, the differences are still noticeable.

-Controls are somewhat unresponsive and stiff. If the player is prone, they cannot immediately change to aiming diagonally down-right; all D-PAD buttons must first be released, if pressed. Additionally, jumping is very unresponsive.

-The player grapples up somewhat slower.

-There are no sprite frames for the player aiming diagonally while hanging on a rail. The player will instead appear aiming directly down or up; rapidly pressing the fire button in a diagonal direction will cause the player sprite to fidget in that direction.

-Holding the fire button with any gun causes the player sprite to fire as if the Machine Gun is equipped.

-Easy Mode does not automatically upgrade acquired gun powerups.

-Neither Konami Code cheat is implemented yet.

-The player cannot gain lives through points.

-No data in the prototype is saved (selected character, settings, current level, etc.) when resetting or powering off the DS.

-In the final, if the game’s saved data is corrupt for any reason, a screen appears after the title screen sequence informing the player of this (and the saved data is erased). Neither of these occur in the prototype.

-During the stages, a bar with a varying color palette appears at the bottom of the upper screen. The colors vary with the amount of action in-game, indicating the system CPU usage and, in extension, the frame rate. As the bar length increases, the color changes from green to red..

-The game tends to lag more easily and frequently than the final game, especially during the 3D stages.

-There is no map on the lower screen for any of the tunnel stages, as shown further below.

-The players’ death animations in the tunnel stages are shared with the side view stages, instead having their own as in the final:


-While confronting a wall in the base stages, pressing R automatically scrolls the screen and the player forward, through the current wall, to the next one that must be destroyed:


This can be repeated until the boss. Any remaining enemies/dangers at the current wall can still harm the player, which reveals that enemies in the tunnel stages are harmful upon contact.

This function can be used at any time when confronting a wall, including while jumping or in the middle of the player’s death animation.

-The tunnel stages’ fade-in transition is faster in the prototype.

-After selecting a stage directly from the Debug Menu, simultaneously pressing L and R freezes the player sprite. The player can now move the character anywhere on-screen. All of the player’s bullets in this mode fire vertically. The top-left corner of the lower screen shows the player’s X-Y coordinates.


-The Pause Menu is very crude. Strangely, a different Pause Menu is used during the Ocean stage and most of the Harbor (Missile) stage. For the latter, the game reverts to the main variant after the missile crashes. Below, the major variant is on the left, while the minor variant is on the right.

pausealt pause1

It appears that the player’s high score was planned to be displayed during gameplay.

-The intermission sequences feature a very crude design. Stages 3, 6 and 8 erroneously use the one for the Jungle stage.

Jungle (also all 3 tunnel stages):










Notice the barely-visible stage name, labelled in handwriting. It also lacks the sound of the player’s footsteps.

-Different Game Over screen:


Selecting Continue freezes the game; selecting Quit sends the game into a black screen.

-After defeating many of the stage bosses, the screen simply fades to black and transitions to the intermission screen. In the final version, the player is shown moving to the right of the screen towards the entrance or general location of the next stage.

Wireless Menu


The following is a list of all the selections from the Wireless Debug Menu, listed in order from the starting option:

Level Jungle
Level Waterfall
Level City
Level Ocean
Level Missile
Missile – Guardian
Missile – Guardian2
Black Viper
Black Viper Cerebrum
Test Tunnel

Test Tunnel appears to be a scrap that may have been intended as a debug 3D stage. This selection appears only in the Wireless Debug Menu. The following appear on the DS screens:

f0u4p 90ulk4d

The host player receives another error message on a blue screen, shown on the left. The guest/joining player is presented with a ray-casting style 3D tunnel, shown on the right, where the game hangs. Notice, however, that the left wall is crudely textured.

The other selections have not yet been tested.

The following transcribes the text around the perimeter of the screen in the Wireless Debug Menu:

Top Left
.: wireless debug menu :.

Top Right
release build

Bottom Left
::: X of 13 ::: *

Bottom Right

*Where X is the menu option highlighted, starting with Level Jungle.

Please consult the following 2 videos to compare with the information presented below:

Game Menu

-The Konami and Wayforward logo screen displays twice (glitch). Additionally, these can be sped up by pressing UP/DOWN/A/B/START/etc.

-Intro sequence consists of crude, mostly colorless illustrations, in the style of comics, and plain text:

introcutscene1 introcutscene2

introcutscene3 introcutscene4


-No title screen with “press start”; current title screen is a placeholder:


Shortly after the title screen is displayed, the game then changes to the main menu. In the final, the title screen and intro sequences alternate constantly until the player manually enters the main menu.

-No Attract Mode demos. Pressing B from the main menu brings the player back to the intro sequence; in the final, it returns the player to the title screen sequence.

-Main menu with slightly different option labels:


-Touch screen functionality is fully implemented for these menus.

-Arcade and Challenge Mode have swapped positions.

-In the final, choosing Arcade Mode will first display a screen to choose between 1 or 2 players before the difficulty is selected; in the prototype, this screen appears after the difficulty selection.

-By default, Easy Mode is highlighted in the prototype, whereas Normal Mode is highlighted in the final.

-The Game Sharing option does not appear in the final:


-Hidden options are already unlocked (Challenge Mode, Bonus Features), including all bonus content.

-The Main Menu’s decorations animate constantly, whereas they animate once in the final.

-There are no label plates; instead, menu sections are displayed as subtitles.

-Main menu sound effects don’t play when Game Menu is first selected. They play after returning to the Main Menu from gameplay (quit Arcade Mode or end a challenge).

–In the final, starting an Arcade Mode session or a challenge plays a gun fire sound effect. In the prototype, starting Arcade Mode plays the regular menu selection sound; selecting a challenge does not play any sound.

Challenge Mode:

-Highly glitchy.

-In the Challenge menu, if the player leaves too quickly, the screen will appear black. However, they are actually still in challenge menu and must either press A (select challenge; can optionally press up/down/left/right to scroll through challenges), or B (return to the rudimentary intro sequence).

-Only the first 5 challenges have label plates and they are generically labelled Challenge 1-5:


However, all 40 challenges are accessible, despite there being no text and the selections, invisible:


Even then, many crash the game; some instantly display VICTORY or DEFEAT and return to the Main Menu. Most do not display DEFEAT when killed, as the player has 99 lives and can continue playing after the first death. Some challenges fail to display VICTORY and play out the stage as a regular session, either leading to the next stage or crashing (also applies to sections of stages that otherwise crash the game, anyway).

-The challenge list has a page indicator at the bottom; in the final, the counter indicates how many challenges, out of 40, are completed.

-In the final, the pause screen during a challenge displays the stage name and the challenge description (seen when highlighting a challenge in its menu) below it, at the very top. This is absent in the prototype. The pause menu here is the same as its Arcade Mode.

-Selecting quit in the pause menu highlights quit (confirmation) instead of cancel; NO is highlighted in the final.

-Quitting from a challenge takes the player to the Main Menu instead of the Challenge Menu. The Pause Menu during a challenge is the same one from Arcade Mode.

-The first 4 challenges are Mutt Hunt challenges (Jungle, Missile, City, Black Viper); the fifth challenge is a Low Ammo one, surviving the Jungle stage with 100 bullets.

-In Pacifism challenges, the player, despite not shooting bullets, exhibits shooting animation (when pressing Y). Shooting while swapping guns (SELECT) in Pacifism challenges occasionally causes a primary level fireball to be shot. In some Pacifism challenges, the player’s gun icons are displayed in the top-left corner of the screen.

-The same effect as above occurs in Low Ammo challenges after the ammo runs out. It also occurs when holding down the fire button in the Classic Laser challenges.

-With the exception of the Rematch challenges, the player will not lose the challenge if they get killed; they are provided with 99 lives.

-The game can be paused during the victory/defeat messages, although the game will still return to the challenge menu.

Different VICTORY and DEFEAT messages:

challengevictory challengedefeat

The player is vulnerable during the messages.

-One of the challenges, taking place in the City stage, features brown colored Proboterror enemies:


-Here are the 40 challenges of this prototype, each followed by its respective final counterpart:

1. Mutt Hunt, Jungle; Bad Guy Blitz 1, Harbor
2. Mutt Hunt, Missile; Pacifism 1, Ocean
3. Mutt Hunt, City; Mutt Hunt 1, Jungle
4. Mutt hunt, Black Viper; Pacifism 2, Harbor
5. Low Ammo, Jungle; Bad Guy Blitz 2, Laboratory
6. Low Ammo, Missile; Gunplay 1, Harbor
7. Low Ammo, Black Viper; Bad Guy Blitz 3, City
8. Pacifism, Waterfall; Rematch 1, Jungle
9. Low Ammo, Ocean; Speed Run 1, City
10. Pacifism, Jungle; Bad Guy Blitz 4, Harvest Yard
11. Pacifism, Missile; Pacifism 3, Laboratory
12. Bad Guy Blitz, City; Speed Run 2, City
13. Bad Guy Blitz, Waterfall; Mutt Hunt 2, Laboratory
14. Pacifism, Ocean; Bad Guy Blitz 5, Jungle
15. Bad Guy Blitz, Missile; Gunplay 2, City
16. Bad Guy Blitz, Jungle; Rematch 2, Laboratory
17. Bad Guy Blitz, City; Accuracy 1, City
18. Accuracy, Waterfall; Friendly Fire 1, Laboratory
19. Bad Guy Blitz, Black Viper; Speed Run 3, Harvest Yard
20. Accuracy, Jungle; Mutt Hunt 3, City
21. Accuracy, Ocean; Accuracy 2, Jungle
22. Speed Run, Waterfall; Gunplay 3, Harvest Yard
23. (blue screen crash); Speed Run 4, City
24. Accuracy, City; Rematch 3, Harbor
25. (unknown), Missile; Accuracy 3, Laboratory
26. Speed Run, Black Viper; Friendly Fire 2, Jungle
27. (blue screen crash); Mutt Hunt 4, Harbor
28. Gunplay, City; Bad Guy Blitz 6, City
29. Speed Run, Black Viper; Friendly Fire 3, Harvest Yard
30. Gunplay, Missile; Gunplay 4, Jungle
31. Gunplay, Jungle; Mutt Hunt 5, Harvest Yard
32. Friendly Fire, Jungle; Rematch 4, City
33. Friendly Fire, Missile; Low Ammo 1, Harbor
34. Gunplay, Black Viper; Friendly Fire 4, City
35. Friendly Fire, Waterfall; Low Ammo 2, Jungle
36. (unknown, possibly Friendly Fire), City; Speed Run 5, Laboratory
37. Rematch, Waterfall; Pacifism 4, Jungle
38. Rematch, Black Viper; Low Ammo 3, Harvest Yard
39. Rematch, Jungle; Speed Run 6, Harbor
40. Rematch, City;Rematch 5, Harvest Yard

Mutt Hunt General:
-There is no mutt counter at the top of the screen.

-If a mutt is missed and it runs off screen, the challenge ends with a defeat.

-The victory message appears immediately upon defeating the last mutt of the challenge; in the final, the player must progress to a certain point to determine if the player gains a victory or a defeat.

Low Ammo General:
-Both Crush powerup levels use ammo rounds in an unpredictable, glitched pattern. Each shot rarely uses just a single round; they can count for a random number of rounds, up to 9. In the final, both use 1 round per shot.

Speed Run General:
-The timer continues to count down while the game is paused.

Accuracy General:
-The counter processes accuracy percentage different from the final. It adds a certain percentage to the current number upon firing a round; then, it either adds or removes a certain amount (depending on if the round was a hit or a miss). In the final, the percentage changes to a new number (increases/decreases) when a round either hits a target or disappears off-screen.

Friendly Fire General:
-Hostage AI coding is incomplete, such as for when they reach gaps and walls, etc.

Rematch General:
-The player isn’t provided the primary level Spread Gun for these challenges, unlike in the final.

-Defeating the boss does not display the victory message; instead, the player is simply taken back to the challenge menu.

Challenge 1 (Mutt Hunt):
-Corresponds to Mutt Hunt 1 in the final.

-Same starting point as in final.

-This challenge features purple mutts, likely a palette error:


-The 6th mutt is in a different location:


In the final, it’s in front of the turret.

Challenge 2 (Mutt Hunt):
-Corresponds to Mutt Hunt 4 in the final.

-The 1st mutt is slightly to the right:


-The 2nd mutt doesn’t run up the incline; it turns back. This makes it more difficult to catch it.

-The Barrier powerup in the end stretch can defeat mutts while they’re idling in the background.

-There are no Proboterrors on the lower path during the end stretch, making this challenge much easier.

Challenge 3 (Mutt Hunt):
-Corresponds to Mutt Hunt 3 in the final.

-After quitting this challenge and restarting it, the player is placed near the halfway point of the stage, atop the building before the wide death pit; this glitch can be fixed only by restarting the DS.

-The 3rd mutt in the final is missing here, at start of the building, on the ground:


-The 6th mutt in the final is missing here, on the ground below the player’s position:


-The 5th mutt of the prototype is located much later than that of the final:


-The mutt on the ground is the 6th in the prototype, 7th in the final; the one on the uppermost platform is the 7th in the prototype, while the 8th in the final is on the platform below it, a bit to the right; the rightmost mutt, on the upper-mid platform, is the 8th one in the prototype:


Challenge 4 (Mutt Hunt):
-Corresponds to Mutt Hunt 5 in the final.

-There are no mutts in this challenge; therefore, it cannot be completed (neither messages will appear).

-Related to the previous note, the player can progress through the entire stage, and even defeat the boss (which freezes the game).

Challenge 5 (Low Ammo):
-Corresponds to Low Ammo 2 in the final.

-The starting point is after the last water segment, before the uphill stretch; the final starts at the beginning of the level.

-The challenge ends upon reaching the boss battle.

-100 rounds of ammo are provided; 32 in the final.

Challenge 6 (Low Ammo):
-The start point is at the very beginning of the missile ascent of the Harbor stage, along the platforms.

-Ends just before the grapple rail that triggers the missile launch.

Challenge 7 (Low Ammo):
-Begins at the start of Harvest Yard (Black Viper); in the final, the player starts atop the climb upon the entering posterior end of Black Viper.

-41 rounds of ammo are provided, but the counter is not displayed due a glitch; in the final, 15 rounds are provided.

-This challenge cannot be completed, as the game crashes upon defeating Black Viper’s first form.

Challenge 8 (Pacifism):
-Corresponds to Pacifism 3 in the final.

-Begins at the start of the ascending portion of Waterfall, on the platform to the right of the standing sniper.

-This version is much harder due to enemies not being removed from the stage for this particular challenge.

-However, it ends much earlier, on the grounds after the second vertically moving platform. In the final, it ends on the platform just before the elevator.

Challenge 9 (Low Ammo):
-Begins at the start of the Ocean stage.

-60 rounds are provided.

-Ends at the start of the segmented fish mini-bosses.

Challenge 10 (Pacifism):
-Corresponds to Pacifism 4 in the final.

-Begins at the start of the Jungle stage.

-Ends much earlier, shortly after the first grapple rail; in the final, it ends at the first sniper after the uphill stretch.

Challenge 11 (Pacifism):
-Essentially the same as Pacifism 2 in the final.

Challenge 12 (Bad Guy Blitz):
-starts at the beginning of the upper and lower highway paths of the City stage.

-Analogous to Bad Guy Blitz 1 in the final in that it has aliens instead of the regular enemies of that stage.

-Ends just after the end of the upper path.

Challenge 13 (Bad Guy Blitz):
-Corresponds to Bad Guy Blitz 2 in the final, with the same winged enemies (different spawning patterns, however).

-Same starting point as Challenge 8.

-Ends at the same point as Challenge 8, whereas the final ends at the same point as Pacifism 3.

Challenge 14 (Pacifism):
-Essentially the same as Pacifism 1 in the final.

Challenge 15 (Bad Guy Blitz):
-Essentially the same as Bad Guy Blitz 1 in the final.

-Differences include the start point being a bit closer to the edge of the platform; the Proboterrors appear only on the upper path; the challenge ends closer to the edge of the platform.

Challenge 16 (Bad Guy Blitz):
-Corresponds to Bad Guy Blitz 5 in the final.

-Same start point as in the final.

-The Proboterrors in this challenge have a corrupt, white palette:


-3 Proboterrors spawn in and around the same spot as player’s start point, killing them right at the beginning.

-Different spawning patterns of proboterrors.

-There are no Proboterror Suicide Bombers.

-Ends a few feet before the final’s end point.

Challenge 17 (Bad Guy Blitz):
-Same start point as Challenge 12.

-Features brown proboterrors (shown above), including a bunch that spawn in the air behind the player upon starting the challenge.

-Same end as Challenge 12; so this is essentially a variant of Bad Guy Blitz 1.

Challenge 18 (Accuracy):
-Corresponds to Accuracy 3 in the final.

-Same start point as Challenge 8.

-Minimum 50% accuracy; 70% in the final.

-Ends at the same location as Challenge 8; in the final, it ends at the platform before the elevator.

Challenge 19 (Bad Guy Blitz):
-Corresponds to Bad Guy Blitz 4.

-Starts atop the climb of Black Viper’s posterior end.

-This challenge cannot be completed and neither end messages appear; the player can continue through to the boss fight.

Challenge 20 (Accuracy):
-Corresponds to Accuracy 2.

-Minimum 25% accuracy; 100% in the final.

-Ends at the same point as Challenge 10; a few feet before the sandbag sniper past the uphill segment in the final.

Challenge 21 (Accuracy):
-The player begins at the start of the Ocean stage.

-Minimum 75% accuracy.

-Ends at the same point as Challenge 9.

Challenge 22 (Speed Run):
-Corresponds to Speed Run 5 in the final.

-Same start point as Challenge 8; the final starts the player a bit further to the left, just before the start of the vertical ascent.

-40 seconds are provided; 30 in the final.

-Ends at the same point as Challenge 8; same as the final.

Challenge 23 (unknown):

Challenge 24 (Accuracy):
-Corresponds to Accuracy 1 in the final.

-The player begins at the very start of the City stage.

-The victory message immediately appears when the stage loads, therefore the details of this challenge in the prototype are unknown.

Challenge 25 (unknown):
-This challenge starts with the appearance of Missile Hugger 3000.

-The player is not on the screen; however, bullets can be heard when the fire button is pressed.

-The victory message immediately appears when the stage loads; because of this, as well as the previous note, further details are unknown.

Challenge 26 (Speed Run):
-Corresponds to Speed Run 3 in the final.

-Starts at the same point as in the final.

-~40 seconds are provided, but the timer does not appear (glitch); 56 in the final.

-This challenge will always result in a failure/defeat. The given time is nowhere near enough to reach the final’s endpoint; however, using the L+R debug functionality reveals that there is no endpoint to this challenge in the prototype, making it impossible to complete.

Challenge 27 (unknown):

Challenge 28 (Gunplay):
-Corresponds to Gunplay 2 in the final.

-Same starting point as in the final.

-The stage is nearly devoid of enemies, save for occasional red and blue running mech soldiers and regular foot soldiers.

-The same restart glitch as in Challenge 3.

-MUCH longer than the final counterpart’s; it ends at the start of the upper and lower highway paths. In the final, it ends a few feet after the first building that is passed after defeating the tank miniboss.

Challenge 29 (Speed Run):
-Essentially a repeat of Challenge 26 (with the same problems), except the player spawns on a Face Hugger Egg at the very left, thus immediately dying when the challenge starts.

-Face Hugger explosion animation is glitched:


Challenge 30 (Gunplay):
-Corresponds to Gunplay 1 in the final.

-Same starting point as the final.

-The player’s gun icons appear at the top of screen, as seen in the screenshot demonstrating the laser prototype weapon.

-The game exhibits significant lag until a short distance past the gap at the end of the split paths.

-Like Challenge 28, the stage is mostly devoid of enemies, save for the submarine mini-boss and Proboterrors.

-This challenge is much longer, ending after reaching near the top of the final ladder during the ascent of the docked missile. In the final, it ends just before the gap past the split paths.

Challenge 31 (Gunplay):
-Corresponds to Gunplay 4 in the final.

-Same starting point as the final.

-Like Challenge 28, the stage is mostly devoid of enemies, except for occasional foot soldiers; the wall turrets are already destroyed.

-Any subsequent retries of this challenge causes the upper screen stage graphics to corrupt; the player must restart the system to revert from this glitch:


-Graphical glitch at the start of every bridge:


-Ends at the same point as the final.

Challenge 32 (Friendly Fire):
-Corresponds to Friendly Fire 2 in the final.

-Starts on the grass a few feet past the last water segment; in the final, the player starts on the grass at the beginning of the stage.

-Hostage locations differ to a certain capacity and most of the hostages are the running woman.

-Ends just past the corresponding point in the final, which can easily trigger the screen to autoscroll to the wall boss here.

Challenge 33 (Friendly Fire):
-Same start point as Challenge 15.

-Many hostages on the upper path are glitchy; they fall through the floor to the lower path, and even through the lower ground and off-screen.

-Ends at the edge of the ground past the split paths.

Challenge 34 (Gunplay):
-Corresponds to Gunplay 3 in the final.

-Starts at the beginning of the stage; in the final, starts atop the climb of Black Viper’s posterior end.

-This challenge cannot be completed, as the game crashes the same way as for Challenge 7.

Challenge 35 (Friendly Fire):
-Corresponds to Friendly Fire 1 in the final.

-Same starting point as the final.

-Hostage locations differ to a certain capacity and most of the hostages are the running man with hair.

-Replaying this challenge after playing others will result in the player being placed at start of the waterfall section of stage, with the victory message immediately appearing, ending the challenge.

-Ends at the same point as in the final.

Challenge 36 (unknown, possibly Friendly Fire):
-Possibly corresponds to Friendly Fire 4 in the final.

-The same victory message issue upon starting as Challenge 24, therefore the specifics to this challenge are currently unknown.

-The same restart glitch as in Challenge 3, but with the victory message immediately appearing.

Challenge 37 (Rematch):
-Corresponds to Rematch 2 in the final.

-The player starts below the elevator, in free-fall just above the death pit; therefore they must immediately move to the right and hold UP to grab the vine. In the final, the player starts on the elevator.

-Defeating the boss crashes the game; therefore, this challenge cannot be completed.

Challenge 38 (Rematch):
-Corresponds to Rematch 5 in the final.

-Starts at the left edge of the lowest platform, during the final climb before the shutter sequence that precedes the boss battle. In the final, the player starts at the lowest platform in the same area.

-Defeating the boss crashes the game; therefore, this challenge cannot be completed.

Challenge 39 (Rematch):
-Corresponds to Rematch 1 in the final.

-Starts at the same spot as in the final.

-Enemies spawn from the left of the screen until the boss battle is initiated.

-Because the player dies when falling into the hole formed by the crumbling ground after the wall boss is destroyed, the defeat message appears. This challenge is very difficult to complete due to this (requires using the helicopter glitch).

Challenge 40 (Rematch):
-Corresponds to Rematch 4 in the final.

-Analogous starting point to the final.

-This is the easiest Rematch challenge to complete in this prototype.

Arcade mode:

-When starting Arcade Mode through the main menu, there is no horizontal screen wipe transition effect when starting the Jungle stage, though it happens when loading it through the debug menu. The transition effect occurs for all side-scrolling levels in the final.

-In the final, pausing the game during the screen wipe effect maintains the effect on-screen. In the prototype, it disappears until the game is resumed:


-The game occasionally starts the player at approximately the halfway point of the Jungle stage when starting a new game.

-Resume game prompt:


Player Select:

-All bonus characters are already unlocked.

-Character names are spelled with a mix of upper and lowercase letters, as shown below; in the final, all letters are capitalized.

-Character sprites are the same scale as during gameplay (as opposed to enlarged in the Character Select of final).

-To select a character in the prototype, the player must press B (previous menu); A does nothing. In the final, A must be pressed to select a character, as B returns to the previous menu without changing the currently selected character.

-In the prototype, selecting a character immediately returns to the previous menu; in the final, the character’s animation freezes and one of their voice clips is played as it returns to the previous menu.

-In the prototype, the character choice is saved after returning to the main menu from Arcade Mode; however, if the player uses an unlockable character during gameplay, returns to the main menu and re-enters the Player Select menu, their attire will be changed to the secret one attained by pressing UP twice.

-Character selection order…
Prototype: Bill, Lance (with Scorpion name), Mad Dog, Scorpion (with Lance name), Jimbo, Sully, Lucia, Sheena, Probotector, Goldenrod
Final: Bill Rizer, Lance Bean, Mad Dog, Scorpion, Jimbo, Sully, Lucia, Sheena Etranzi, Probotector

-Bill Rizer is labelled simply as Bill:


-Lance Bean is labelled simply as Lance. In addition, his name is swapped with Scorpion’s:

lance scorpion

-Mad Dog:


-Sheena Etranzi is labelled simply as Sheena:


-Lucia and Probotector:

lucia probotector

-Jimbo and Sully:

jimbo sully

-Strangely, the selection of characters includes the gold variant of Probotector as a separate character, named Goldenrod:


Probotector has the silver default and the blue alternate attires only, while Goldenrod has the gold attire and the purple alternate attire (press UP twice in both cases).

-A sound effect plays when pressing UP/DOWN, but not when browsing characters (opposite in the final).

-Lucia is green by default in this prototype; press DOWN twice to get the blue attire (opposite in the final). her third secret attire, complete purple, is selected by pressing A once.

-Sheena has her blue attire by default (black is the default in the final). Her third secret attire, from pressing A once, is not black, but instead a unique teal android appearance; the black one is absent in the prototype.




Features Starting Lives, instead of VOICE SFX. They can be 3, 5, or 7:


In the final, the starting number of lives (including per continue) is determined by the difficulty setting. Easy, 10; Normal, 5; Hard, 3.

Erase Data does nothing.

Bonus Features:


-Emulated Games provides the NES versions of Contra and Super Contra. However, there’s no option for aspect ratio and the player cannot return to the Game Menu once in the emulated games. Emulation is highly rudimentary, with significant problems with audio emulation.


-Museum contains misaligned, disorganized (ex: repeats) and improperly sized images, as well as different, misaligned text. Several of the featured game screenshots are different in the prototype. The following are all of the entries, with screenshots in the order that they appear:

Arcade Contra’s entry shows Gryzor’s title screen instead of Contra’s. Its name plate reads Gryzor instead of Contra.


The above image appears twice, consecutively.

musgry2 museum

musgry4 musgry5

musgry6 musgry7

NES Contra’s entry shows Probotector’s box art instead of Contra’s (North American). Its name plate reads Probotector instead of Contra.

musconnes1 musconnes2

musconnes3 musconnes4

musconnes5 musconnes6

musconnes7 musconnes8

Arcade Super Contra:

mussconarc1 mussconarc2

mussconarc3 mussconarc4

mussconarc5 mussconarc6


NES Super Contra’s entry shows Probotector II’s box art instead of Super C’s. Its name plate reads Probotector II instead of Super C.

mussconnes1 mussconnes2

mussconnes3 mussconnes4

mussconnes5 mussconnes6

mussconnes7 mussconnes8

Operation C’s entry is either absent or is incorrectly incorporated such that switching to it crashes the game.


Contra Force:

muscf1 muscf2

muscf3 muscf4

muscf5 muscf6

Contra III’s entry shows Super Probotector’s box art instead of Contra III’s. Its name plate reads Super Probotector: Alien Rebels instead of Contra III: The Alien Wars.

musciii1 musciii2

musciii3 musciii4

musciii5 musciii6

musciii7 musciii8

Contra: Hard Corps’ entry shows Probotector’s box art instead of Contra: Hard Corps’. Its name plate reads Probotector instead of Contra: Hard Corps.

muschc1 muschc2

muschc3 muschc4

muschc5 muschc6

muschc7 muschc8

Contra: Legacy of War’s entry shows the Saturn port’s box art instead of the Playstation original’s.

musclow1 musclow2

musclow3 musclow4

musclow5 musclow6


C: The Contra Adventure:

muscadv1 muscadv2

muscadv3 muscadv4

muscadv5 muscadv6

Contra: Shattered Soldier’s entry shows the PAL box art instead of the cropped, filtered North American box art.

muscss1 muscss2

muscss3 muscss4

muscss5 muscss6

muscss7 muscss8

Neo Contra’s entry shows the full North American box art instead of a cropped, brightened North American box art shot.


First image, shown above, appears twice (1st and 3rd).

musnc2 musnc3

musnc4 musnc5

musnc6 musnc7

The overall default entry images being of the European releases supports this being a prototype of a planned European release.

The Bonus entry has images that could be progressively unlocked (counter always reads 3/10). In the final, the text reads Completed all the challenges, did you? Then step inside, soldier… more content awaits.


musbon2 musbon3


Bonus images 2 and 5-10 remain locked/hidden.


The Extra Content text on the lower right corner erroneously remains on the screen until the player exits completely from the museum.

-Comic Book menu:


Both comics are present, but the comic viewer lacks the page flipping sound effect; however, pressing UP/DOWN plays a sound effect for a few presses. There are also a few controls overlaid on the lower screen (next/previous page and return buttons. Flipping through pages simply uses a sliding effect here; in the final, there is also a fade-to-black effect.

There is a page counter:


The Contra 4 comic contains only 3 pages; all are variations of the same strip:

con4comic1 con4comic2


-Sound Test:


In the final, the sounds are listed as SE 001-135; in the prototype, the sounds are given specific names. There are only 108 sounds and not all are heard during gameplay, or at least what’s directly accessible to play (missing in gameplay, the game crashes at segments, etc). None of the music in this menu actually plays. The sound effect and BGM orders are also different from the final.

The following is a comparison of the sound effect and BGM entries in the prototype sound test and its corresponding final entry names (prototype name first, final second).

Sound effects:
crush1 shot; SE 004
crush2 shot; SE 005
crush explosion; SE 006
fire1 shot; SE 007
fire2 shot; SE 008
grapple gun shot*; SE 018
grapple gun zip*; SE 019
hunter1 shot*; SE 009
hunter2 shot; SE 010
laser1 shot*; SE 011
laser2 shot; SE 012
mac1 shot; SE 013
mac2 shot*; SE 014
spread1 shot*; SE 001
spread2 shot*; SE 002
rapid shot* (more distorted); SE 003
enemy damaged; SE 030
enemy explode; SE 015
enemy shot lobbed*; SE 016
helicopter blades LOOP; SE 020
menu confirm startgame*; SE 022
menu go back options confirm* (longer); SE 023
menu switch option*; SE 024
pickup collected*; SE 026
splash water*; SE 027
enemy dies*; SE 031
damage; SE 029
bone platform smash 1; SE 055
bone platform smash 2*; SE 037
bones crumbling*; SE 038
claw hits ground*; SE 039
earth shaking LOOP; SE 040
egg sac bursting*; SE 041
fleshy pit opening; SE 042
gastric fall*; SE 043
gastric rise*; SE 044
gurgling bellows LOOP; SE 045
helicopter explosion long; SE 046
helicopter rotors malfunction*; SE 047
redfalcon sink ground; SE 048
roomshaking alien scream; SE 049
screen clearing blast*; SE 050
stab fleshy floor*; SE 051
titanic beam shot*; SE 052
titanic beam shot LOOP; SE 053
xenomorph shriek*; SE 054
acid burn*; SE 064
alien jump out*; SE 065
barracuda screech*; SE 066
blood spurt*; SE 067
boat explode 1; SE 068
boat explode 2; SE 069
boat explode 3*; SE 070
exploding gore 1*; SE 071
exploding gore 2; SE 072
exploding gore 3; SE 073
flying man death; SE 056
larvae beast roar; SE 057
laser burst*; SE 058
motorcycle zoom; SE 059
ram concrete dam; SE 060
scuttling bugfeet LOOP; SE 061
twin snakes screech*; SE 062
waterskimmer jump; SE 063
mosquito death*; SE 074
wave of fire*; SE 075
wave of fire LOOP; SE 076
winged alien warp; SE 077
alien tail stabbing*; SE 096
bridge explosion*; SE 078
carpet bomber*; SE 079
claw gripping metal*; SE 080
crumbling concrete LOOP; SE 082
crumbling concrete break*; SE 081
fiery explosion blast*; SE 083
horrible shriek*; SE 084
horrible shriek short*; SE 085
huge explosion*; SE 086
mortar fire; SE 087
object hits bones*; SE 088
sick human gooey explosion*; SE 089
sick human shriek; SE 090
track gun blast*; SE 091
track gun moving LOOP; SE 092
waterfall loop1; SE 093
waterfall loop2; SE 094
waterfall loop3; SE 095
guardian missile fire; SE 105
guardian smash down; SE 097
large missile blastoff; SE 098
missile countdown 1* (longer); SE 099
missile countdown 2 beep*; SE 100
missile lockon; SE 101
missile smash building 1*; SE 102
missile smash building 2*; SE 103
twinsnakes rising from water*; SE 104
alien eye healing; SE 115
alien heartbeat*; SE 116
metal canister clank; SE 117
metal head falling; SE 106
metal skeleton crawl LEFT*; SE 108
metal skeleton crawl RIGHT; SE 109
metal skeleton crawl background LOOP*; SE 107
metal skeleton peel wall*; SE 110
metal skeleton shriek; SE 111
motion tracker beep*; SE 112
spikes ceiling*; SE 113
steam burst*; SE 114

*noticeable difference from the final

Music tracks:

The following sound effects from the final version’s sound test are absent in the prototype’s:
SE 017
SE 021
SE 025
SE 028
SE 032-SE 036
SE 118-SE 135

The following music tracks from the final version’s sound test are absent in the prototype’s (and in the prototype’s game data altogether):

-Interview displays the following 2 pages of text, stating to be for Daniel Kellogg:

interview1 interview2

Menu Text

The following is a comparison of menu text for all shared menu items/options. To the left of the semicolon is the prototype; to the right, the final.

Main Menu; MAIN MENU

Challenge Mode; CHALLENGE MODE
This is Challenge Mode!; Think you’re a hot shot? These challenges will test your skills to the limit.

Arcade Mode; ARCADE MODE
This is Arcade Mode; An experience so classic it’s practically coin-operated.

This is Player Profile; Draft your favorite soldier.

Options; OPTIONS
This is Options; Configure the game.

Bonus Features; BONUS CONTENT
This is Bonus Features; Celebrate Contra’s 20th Anniversary.

Challenge Mode; CHALLENGE MODE

As previously mentioned, each challenge is generically numbered in the prototype (ex: Challenge 1); they also do not correspond to the same numbers as in the final. The first 4 challenges are Mutt Hunt challenges; their descriptions read Defeat all 8 Man Faced Mutts in (the Jungle/the Missile/the City/Black Viper).

In the final, the 3rd challenge is named Mutt Hunt 1, for example; its description reads:

Defeat all man-faced mutts.

In the prototype, Challenge 5 is a Low Ammo challenge; its description reads Survive the Jungle with 100 bullets.

In the final, the 35th challenge is named Low Ammo 2; its description reads:

Get to the end with limited ammo.

Arcade Mode; ARCADE MODE

Easy; EASY
This is Easy Mode; Not a hardcore gamer? Consider this Boot Camp.

Medium; NORMAL
This is Medium Mode; Lock and load, soldier. It may be called Normal, but this is no picnic.

Hard; HARD
This is Hard Mode! Watch out; Think you’re the master of 2D action? Not anymore, you’re not.

Single or Multiplayer; GAME TYPE

Single Player; SINGLE PLAYER
This is Single Player; It’s you against an endless alien army.

Multiplayer; MULTIPLAYER
This is Multiplayer; Play Contra the way it was meant to be played: with a friend!

Load Suspended Game?; Resume Game?

Yes; Resume Game
Yes, Resume my game; *

No; Start New Game
No, delete my game; *

*The description in the final is the same for both selections (static text): You quit mid-game! You can spend one Continue to resume from the start of your current level.


Scorpion; LANCE BEAN (Scorpion and Lance names switched in prototype)
Mad Dog; MAD DOG
Lance; SCORPION (Lance and Scorpion names switched in prototype)
Jimbo; JIMBO
Sully; SULLY
Lucia; LUCIA
Probotector; PROBOTECTOR

Options; OPTIONS

Erase Data; ERASE DATA
This is Erase Data; Erase all saved player data.

Erase Data; ERASE DATA

Yes; YES
Yes Erase data; Yes, erase data.

No; NO
Don’t Erase Data; Don’t erase data.

Data Erased; DATA ERASED

Bonus Features; BONUS CONTENT

Emulated Games; CLASSIC CONTRA
This is Emulated Games; Enter the museum’s hands-on exhibit and experience the birth of a genre.

Museum; MUSEUM
This is the Museum; It’s been a wild 20 years. Stop inside to learn all about the storied history of Contra.

This is the Comic Book; Experience the Alien Wars in graphic novel form, as drawn by Atsushi Tsujimoto.

Sound Test; SOUND TEST
This is the Sound Test; You’ve heard ’em! You love ’em! Now listen to them again.

Interview; INTERVIEW
This is the Interview; Hear noted series Producer Nobuya Nakazato’s thoughts on the Contra series.

Emulated Games; CLASSIC CONTRA

Contra; CONTRA
This is Contra; Pitted against the galaxy’s foe, either you win or the whole world loses.

Super C; SUPER C
This is Super C; A killer instinct is all that matters. And if your trigger finger lacks stamina, Earth will lack a future.

Comic Book Menu; COMIC BOOK MENU

This is Comic 1; This comic is based on Contra III: The Alien Wars (1992).

This is Comic 2; An all-new comic based on Contra 4 (2007)!

Sound Test; SOUND TEST

Prototype menu description:
Press A to PlayPress Y to Stop

Final menu description:
Press the A Button to Play
Press the X Button to Stop

Background Music; BGM

Sound Effects; SOUND EFFECTS


-Almost all powerup locations are different from the final version. They’re either swapped, missing or found in different locations.

-Weapon powerup pickups don’t disappear.

-The player’s powerup gun icons (currently equipped powerup gun) are glitched; they don’t properly display the currently held powerup gun.

-No sound effect plays when swapping between the player’s 2 guns.

-The player can cycle through all guns in the game by pressing SELECT. This includes both power levels of each powerup gun.

-If the player holds an upgraded powerup gun, they can discard only a single powerup icon. This reverts their gun to the Normal Gun; the upgraded power level is ultimately lost, as a result.

-Most guns are present and are mostly the same in appearance and functionality as in the final release. An interesting exception is the upgraded Crush Missiles, where the missile sprite is instead that of the V Homing Missiles prototype weapon:


However, in the 3D stages, numerous guns are different from the final. The majority are simply aesthetic differences, with the exception of the Laser Gun.

The Crush Missiles have a slightly different appearance and are more difficult to see. The primary level is on the left and the upgraded level, on the right:

basec1 basec2

Both forms of the Fireball Gun also have slightly different projectiles from the final. Their colors are less vibrant (primary on the left, upgraded on the right):

basef1 basef2

Both forms of the Homing Missiles are also different from the final. The missiles are smaller, finer and, as a result, much more difficult to see (primary on the left, upgraded on the right):

baseh1 baseh2

The primary level Laser Gun fires slightly darker and thinner projectiles:


The upgraded Laser Gun is glitched. It fires a constant, large blue beam that extends to the far end of the tunnel, making a loud, grinding noise and inflicts no damage.

The Classic Laser Gun prototype weapon is mostly the same as final. However, it is silent and lasers aren’t continually fired at an interval when the fire button is held down.

The V Homing Missiles prototype weapon, also silent, use regular homing missile sprites and fire a volley of 5 missiles per burst; the rapid fire rate is excessive, unloading several volleys of 5 missiles in short succession, creating a dense spray. Missiles will be fired rapidly as long as the fire button is held down. Similar to the Spread Gun in the NES and SNES Contra games, the spread formation and number of missiles per volley breaks down as more missiles are present on-screen, in order to prevent significant lag. The rapid fire rate may be identical to that of the Machine Gun, with the player’s powerup icon even becoming the M upon firing:



-Some enemies/bosses have different hit points on the various difficulty settings compared to the final release.

-There is a noticeable delay between the Grassy Knoll turret enemy in the first stage (camouflaged in the grass) rising up and firing its first shot. Additionally, it can be stood upon:


-Many enemy patterns/spawns aren’t randomized as in the final version.

-Steel turrets have a different destruction sound effect.



-No sound effects for the helicopter, (splash, etc.), snipers, turrets, track car mini-boss.

-Foot soldier spawning spots/patterns are slightly different.

-Some platforms aren’t yet coded for the player to drop down from.

-The player can get killed while ducking in the water. Additionally, it is possible to fire while underwater.

-Slightly different player respawn spots.

-Different placement for the first sniper:


-F powerup is S, instead:


-Shortly after the previous S powerup, another S powerup appears, which is absent in the final version:


-S powerup is C, instead:


-This sniper is on the lower platform; in the final, he’s at the upper one:


-This grapple rail is much higher than in the final, emphasizing the use of the Grapple Hook:


-This bridge’s suicide bomber is absent; M powerup there is H, instead, and flies in the opposite direction:


-A camouflaged turret is in the place of a sniper. Additionally, notice the turret’s misaligned bullet:


-C powerup is H, instead; it lands in an incorrect spot:


-The suicide bomber of the bridge above the C powerup crawls closer to the bridge’s center before detonating; in the final, he simply latches on and detonates:


-Different enemy placement in the section immediately following the suicide bomber described above:


-The next suicide bomber also crawls closer to the bridge’s center before detonating:


-Different enemy placement in the section following the suicide bomber described above. Also, S powerup is F, instead:


-These towers are slightly bigger and the grenadier is not at its center:


-This tricky powerup pod holds an F powerup, instead of an H:


-In the following section, the final has a very different enemy placement. The grenadier and turret are replaced by a sandbag sniper in the final; where the player is standing is supposed to be a grenadier; the top-most sniper is replaced by a camouflaged turret; the lower sandbag sniper is replaced by another grenadier:


-Track car mini-boss has significantly more health. An L powerup appears near where the mini-boss appears; a C powerup appears at this point in the final:


The L powerup will actually rest atop the mini-boss if it lands lands on it, until the cannon slides away to a side. In the final, the powerup falls through the cannon to the ground.

-The track car’s fireballs inflict half as much damage to enemies compared to the final.

-There’s no animation for the player exiting the track car; they just exit immediately and stand atop, to the right of the hatch.

-This sandbag sniper is replaced by a regular sniper in the final:


-Powerups right before the boss are L and M, instead of F and L; they also fly in the opposite direction (from left of the screen here, instead of right in the final), at the same time. Additionally, the 2 background trees are absent from that spot in the final:


-The wall boss has no sound effects, except for its laser beam blast (the charge-up is silent); the sound itself is quieter. In addition, the upper core in the second phase (organic one revealed after the first phase’s core is destroyed) is much stronger than in the final. The boss components’ damage sounds vary in volume based on the weapon used and sometimes the angle at which they are being shot.

Additionally, if any running foot soldiers are still on-screen when the screen stops at the wall boss, those enemies will simply run through the wall (in the final, they run back in the opposite direction upon reaching the wall).

-End-of-stage sequence is not yet properly coded: when the ground collapses beneath the player, sending them falling off-screen, it is counted as a death, costing the player a life. The player then respawns and floats in the air. Also, after the boss destruction animation completes, there’s no delay before the ground collapses (in the final, the stage victory tune plays before the sequence). The helicopter also leaves the screen earlier.

Additionally, if the player hangs on the helicopter rail as it flies away after the boss is defeated, they are actually taken backwards in the level (in the final, the helicopter flies off-screen and the player is automatically slid off the rail). This produces various glitches: enemies and the track cannon mini-boss respawn, level graphics and the wall boss sprite scroll vertically. However, the game still completes the boss destruction sequence; as a result, the player is taken to the next level shortly.

Laboratory (Waterfall):

-The stage is referred to as Waterfall in this build.

-Vent bugs have slightly different placements and spawn more frequently; they also lack sound effects.

-Meat puppets lack their screaming sound effect.

-In the laboratory section, the player is able to backtrack a few feet (the screen scrolls back).

-Slightly different foot soldier placement and spawn patterns in the waterfall section.

-Boulders fall out of holes less frequently in the waterfall section.

-The animated waterfall background graphic is very different from the final, as shown in the shots below. It is much simpler in appearance and animates much slower; there is also no relative motion to add a parallax effect when the screen scrolls up/down.

-A few feet ahead of the start of the stage, a C powerup appears in the final; no powerup appears in the prototype.

-M powerup is present, whereas no powerup appears in the final at this spot:


However, at the gap after this spot, an L powerup appears in the final, whereas no powerup appears in the prototype.

-C powerup appears, instead of the Special:


-H powerup appears at this spot where no powerup appears in the final:


-H powerup instead of M:


-A flying pod with an M powerup appears here, where no flying pod appears in the final; the small hole on left sometimes doesn’t spawn a boulder; the top-left is a turret, instead of an F powerup.


-2 grenadiers where there are no enemies in final:


-The gun turret in the lower right section does not appear in the final:


-C powerup, instead of B; occasionally, the hole on the right doesn’t spawn a boulder:


-A flying pod with an S powerup appears right below this spot in final, but is absent here:


-Notice the scuba enemy in the water and the grenadier at the top-right; in the final, they’re absent and instead, another sniper is present on the platform southwest of the grenadier:


-The sniper beside the scuba enemy does not appear in final:


-A flying pod with an M powerup appears; there’s also a sniper enemy on the right. Neither appear in final:


-This turret is a pod with a C powerup in final; there should be a sniper on the platform to its right:


-The platform above the player should have a grenadier; the platform at the far right should have a sniper; that pod yields an S powerup, instead of an M:


-Instead of that sniper, there should be a scuba enemy right above him and a grenadier more to the middle of the rock platform:


-This S powerup should appear a bit higher and to the right:


-These 2 snipers don’t appear in the final; instead, 1 should appear on the mid/upper-left platform:


-There should be a grenadier on the lower-right platform, another sniper on the platform above that, and the M powerup is instead an F powerup in the final:


-The soldier that the boss impales does not produce any gore:


-The boss attack pattern is different. It starts by attempting to stab the player with its tail; here, the tail is much higher than in the final:


However, it also uses a low tail attack. It spits only 3 projectiles at a time, randomly in 5 preset narrow directions, as opposed to sweeping broadly, from left to right. When it pulls the ground up to its head, it does not spit projectiles or perform any attack. Its ground-slamming claw attack is more static, as it stands in 1 place and only hits the ground once with either one or the other claw (randomly chosen).

Thus, its attack order and pattern: high tail stab, 1 claw, low tail stab, projectiles, raise ground, repeat.

The boss has no destruction frames. In its second phase, again, it spits projectiles in an unpredictable way:


Additionally, the second phase has no death frames and the screen doesn’t shake when its head crashes into the ground.

-The scenery at the base entrance is incomplete:


Base (Tunnel 1):

-The stage is referred to as Tunnel 1 in this build.

-Absolutely no enemy sound effects play.

-Destroyed turrets/cores and walls lack destruction animations.

-Powerup guns remain very briefly and disappear without blinking; they often can’t be picked up.

-The M powerup on the first screen bobs up and down in the air:


-2nd screen yields an M powerup instead of an L:


-Slightly different enemy pattern on the 3rd screen, and the enemies attack more aggressively (!)

-3rd screen yields S powerup twice, instead of an F:


-Rollers cannot be destroyed and don’t kill player:


-5th screen yields an L powerup instead of an S; plasma turrets appear on this screen instead of rollers as in the final; only the front-right 2 plasma turrets pop up (and in extension, can be destroyed):


-6th screen features only harmless rollers, instead of plasma turrets as in the final:


-Stage boss does not attack with its projectile; it uses its mirror image phase throughout the entire battle, speeding up as it gets more damaged:


-Boss destruction animation is highly rudimentary:


-The stage ends simply by fading to black. In the final, the player aims rightward (reverting to the side-view stage sprite) and runs to the right shortly after. The prototype also usually crashes at this point.

-Overall, there is little to no lighting variation throughout the stage.

Harbor (Missile):

-The stage is referred to as Missile in this build.

-The start lacks the screen wipe effect; instead, the effect consists of a black lower screen and a brightening blue upper screen before the level immediately appears:


-The first enemy is not centered.


-Here, an F powerup appears from the right on the upper screen in the final:


-This C powerup should be an H; at this point, a Special should appear from the right on the lower screen in the final; the layout of the lower rails after this section is different from the final:


-The layout of this section is different in the final; there’s no manned turret on the lower platform; to his right should be a scuba enemy; no powerup should appear at this spot:


-There should be a sniper at the far right of the platform and another sniper at same position of the platform below, in the final; also, an L powerup should appear from the right of the top screen:


-An F powerup appears in this area, whereas no powerup appears in the final:


-A C powerup appears at this point in the final:


-The submarine mini-boss has a slightly different attack pattern; its primary cannon on the right fires more orange bullets when the submarine is returning to the left of screen:


Its machine gun turret takes less damage to destroy. The mini-boss cycles through the full timing of every weapon component’s attack sequence, even if any of them are destroyed. In the final, the ones that are destroyed are skipped until an inact component is reached.

-S powerup instead of M; no Proboterror enemies appear in the lower screen in the prototype:


-Another S powerup, instead of L:


-C powerup instead of F:


-The gap behind the player here is much smaller in the final:


-There’s no manned turret at this point; no blue enemies begin to appear here in the final:


-Spawn locations and patterns of winged enemies differ from the final. Platform layout of the entire climb also differs, as shown above.

-This manned turret is absent and the ladder layout is different in the final:


-This long ladder is spliced up; there’s no manned turret and the S powerup appears a bit earlier in the final:


-Again, more layout differences from the final; none of those manned turrets appear in the final and the M is more to the right in the final.


Also, in the above screenshot, there should be a high jump that requires a long grapple to reach in the final; here, grappling is not needed.

-In the final, these 2 poles are connected into 1 long continuous pole:


-The Missile Hugger 3000 rarely punches the player; it mostly climbs to the top and bottom of the screen and launches 3 missiles from those ends.

-The 3 vertical poles and the horizontal one below it are much shorter in the final (image).


-The entire missile riding sequence is full of differences: small rocket patterns, grappling switches locking/unlocking and especially the booster flames gauntlet. The small rockets have a different order/pattern of appearance and are more difficult to destroy or avoid (they’re faster). In this build, the player immediately latches onto a lock that they jump up towards; in the final, they first reach the peak of their jump and then latch on when falling back down. The gauntlet here has a different pattern, is longer and due to the smaller delay before a burst, is much more difficult to survive. The booster and fire sprites are also different, with the burst puffs seemingly lifted from Contra III: The Alien Wars:


Also, while hanging on the missile locks, the player’s aim becomes fidgety.

-The stage boss (Missile Hugger 3000’s second phase) doesn’t have the tricky diagonal punch that the final version has.


-The start uses the fade-in transition instead of the horizontal wipe effect.

-No water sound effects.

-The player’s jet bike does not get destroyed when the player loses their last life, whereas it does in the final.

-The alien piranha gauntlet is longer and more intense. The piranhas lack sound effects.

-Powerups don’t slide across the water surface, to the left as in the final; they sink off-screen:


They also slide across top of the jet bike if they land on it, during the interval before the player respawns after dying.

-M powerup instead of C:


-S powerup instead of M:


-C and M powerups instead of F and L:


-Segmented fish mini-bosses are a bit easier due to broader and more predictable jumping patterns. They also lack sound effects.

-C and S powerups; none appear here in the final:


However, during the air soldier guantlet right after these powerups, a Special powerup appears in the final, which is absent in the prototype.

-The water troops exit from 2 submarine doors only, and these doors appear incomplete in design:


-The armored soldier mini-boss hand-signals 1 air soldier at a time to exit the door behind him (up to 4 are summoned in the final). He hand-signals differently and more frequently:


Also, in this section of the final, an H powerup appears that doesn’t appear in this version.

-The game only progresses after both the mini-boss and air soldier are destroyed (or the latter flies off-screen); in the final, destroying the mini-boss automatically destroys the rest of the enemies on-screen.

-Defeating the armored soldier does not destroy his ship.

-H powerup (2nd one in the screenshot) instead of S in final; also, the alien piranhas aren’t rendered correctly (appear above water):


-If the stage boss’ eye is attacked when it first appears on-screen, the game crashes. Also when it first appears, it doesn’t charge to right as in the final. It instead slowly move from left to right, about halfway across screen, randomly launching fin spines. It then charges the rest of the way. No alien piranhas appear throughout the battle. In general, this boss battle is extremely unstable and crashes the game at random.

Factory (Tunnel 2):

-The stage is referred to as Tunnel 2 in this build.

-A particularly resource-demanding stage, exhibiting slow frame rates and frequently crashing the game.

-No powerups appear at any corridor in the prototype.

-Soldiers and wall gun turrets have different firing patterns compared to the final.

-Turrets, targets and walls have simpler destruction animation, lacking all explosion elements. Their destroyed forms are often misaligned on the walls:


-Destroyed targets produce much more smoke than in the final:


-Grenadier mechs are incorrectly programmed, as their grenades disappear almost immediately after being launched. Sometimes, they do not follow the player’s position; or they simply do not attack and stand in place. They also have an additional standing state:


Only the first 2 in each of corridors 1, 5 and 6 actually appear. After they’re destroyed or run off-screen, no additional grenadier mechs appear.

They will sometimes remain motionless at a position until destroyed.

-The player cannot destroy the protective shell on the core targets; as a consequence, the player is potentially stuck on the first screen:


R must be pressed to progress further.

-The 2nd corridor is much different from the final. Here, its first 2 walls consist of 4 gun turrets:


On the 2nd wall, the origin of the bullets are significantly misaligned, firing from outside of the level boundaries:


The 3rd wall consists of 8 targets arranged near the bottom:


The rings above the targets may be outlines of the larger target seen later in the stage.

The final version consists of 2 gun turrets near the ground on the first wall, followed by 2 near the ceiling on the second; the third wall consists of a target at the top-left and bottom-right corners, and gun turrets at the top-right and bottom-left corners.

-Winged mechs at the 3rd corridor frequently get stuck for a moment when descending from the ceiling.

-The 4th corridor is much simpler in appearance:


Plasma cannons on the ground, whose projectiles here are harmless, are further away and are different in appearance:


They also only prop up one at a time, whereas more than one can rise to attack in the final.

The player must destroy the main rotating target and also all 3 plasma cannons. In the final, only the rotating target must be destroyed to proceed.

-The target boards that approach the player at the 5th corridor are much different from the final. They are much simpler in design:



These take significantly more damage to destroy; the first 3 that appear erroneously do not have red targets (shown above). They approach the screen much more slowly and enemy soldiers can shoot through them. They remain at the closest point in front of screen for much longer before retracting underground.

Likely due to incomplete coding, the boards must be destroyed in a specific and unusual way. When one appears with a target, the board must be shot until it’s destroyed; its target will remain very briefly in place and then disappear. The target must be destroyed in that minute time span. This must be repeated for all 3 boards. In the final, simply destroying a board will also destroy its target.

-The 6th corridor also very different:


It features blue targets near the ceiling; in the final, they’re the shielded red targets and are closer to ground. These blue targets can’t actually be destroyed; they instead seem to control the crusher, when shot, in a random way. Each one also lights up when shot; however, when one is lit, the other remains or reverts to being unlit.

The crusher’s programming is incomplete; it is harmless and seems to operate after the player attacks a blue wall target. After stomping down twice, it retreats into the ceiling and does not return.

The corridor wall destroys shortly after the crusher exits the corridor through the ceiling.

If R is pressed at this corridor, skipping it, the last section of the stage (boss fight) will not be rendered and the player is prevented from scrolling (and in extension, progressing) forward:


-The entire boss battle is significantly different. For the first phase, the robot is already in view, awaiting the player from afar.

From the 6th corridor:


At the 7th (last/boss) corridor:


In the final, the player stops at a seemingly dead-end wall, which the robot then breaks through. This means the player is also much closer to the boss in the final.

The robot’s arms animate as though they are holding open seal doors.

The boss’ flame is visually much simpler:


The flame patterns are different. The 1st spray moves across the ground; the 2nd moves mostly across the ceiling (although the player can get killed if standing near the left end or anywhere between the midpoint and the right end); the 3rd is a sinusoidal pattern, as the boss alternates the flame upwards and downwards every few feet as it moves across the screen.

The 3rd pattern, absent in the final, is interestingly a more elaborate one. All 3 occur from left to right of the screen.

In the final, the 1st flame pattern moves across the ground, from left to right; the 2nd is from right to left, also across the ground; third is from left to right, across the ceiling.

-The sequence after defeating the boss’ 1st phase is very different in the prototype, comprising an additional phase not present in the final. Here, the boss crawls up to the player and then crawls in place:


Occasionally, it stops and swats the ground with either of its hands randomly, which can kill the player if they are standing in that area:


The player must shoot the robot’s head until both characters run further back in the stage to begin the 3rd phase (2nd in the final). Both characters retreat much faster here than in the final. When the player character arrives at the phase 3 location, they appear to drop down from the air.

In the final, the robot chases the player backwards in the stage from phase 1, directly to the location of the last phase.

-In the prototype’s 3rd boss phase, where the player is much further back from the boss than in the final, the seal door’s design is different targets are green, instead of red:


-Here, the flame patterns are also different. 1st one moves across the ground, from left to right; 2nd moves slightly above the ground, from right to left; 3rd moves closer to the ceiling, back to the right. These occur in short succession. In the final, it simply repeats its phase 1 flame patterns. Throughout the entire phase, the robot itself remains stuck in the animation state as if it’s attempting to push the doors open/apart.

-The green targets blink when shot, even during the flame attacks; however, they do not close during this sequence.

-The boss destruction animation is surprisingly more complex/elaborate here. In final, head drops to ground and slightly tilts, but remains in place. Here, upper portion of head is sectioned off, is thrown up a few feet before dropping down; it then bounces across ground, hitting the walls before finally rocking in place to a stop:



-The stage’s lighting never turns dark throughout the boss battle in the prototype. The boss itself does not blink when damaged. Its movement and animation are much simpler in general compared to the final. Overall, there is little to no lighting variation throughout the stage.


-Starting area is slightly different; also, the player can immediately move to the right when the stage loads:


-Entering this stage from the debug menu occasionally starts the player falling from the upper screen:


-C powerup instead of F; also, the car pileup in the background is different:


-H powerup instead of M:


-There are no civilians or man-faced mutts here in the final:


-Another man-faced mutt that is absent from the final. Also, the grenadier is very aggressive in the prototype; he can launch a grenade far and very fast, as shown with the grenade in front of the player:


-Another man-faced mutt that is absent from final (image).


-A blue footsoldier breaks through the window above the manned turret in this version; in the final, this window is already broken and, therefore, no soldier should appear:


-In the final, there’s no manned turret; instead, there’s a heavily armored black sniper that is stationed more to the right. Also, an H powerup appears here in the final:


-C powerup appears from the left, but no powerup appears here in the final. Additionally, the meat puppets are placed differently:


-A heavily armored black sniper is found at the top-most platform in the final:


-The tank mini-boss fidgets constantly and is completely silent:


-The rooftop contains more meat puppets than in the final:


-Another man-faced mutt that is absent from the final:


-In the final, a C powerup appears from the left of the lower screen and the edge of the rooftop above contains a grenadier; both are absent in this prototype. Additionally, the rail is longer in the final:


-This section differs in layout (no gaps and ground is flat). Crab mini-boss has differently colored mouth pincers.


Its lasers and flames are darker in color:

citycrab2 citycrab3

Its attack pattern slightly differs, in addition to its death animation. When defeated, it collapses and explodes, but intact, to the bottom of the screen; in the final, it explodes into pieces that fall as the screen turns slightly white.

-A (possibly unintentional) safe spot that is not present in the final:


-Another man-faced mutt that is absent from the final:


-The F powerup appears a bit ahead in the final. Also, a grenadier appears on the ground below the player in the final:


-A heavily armored black sniper appears on the platform below in the final:


-A Special powerup appears on the left of the lower screen in the final:


-An H powerup appears on the lower screen in the final:


-In this section of the stage, the player’s bullets cannot pass through the overhead highway in the final, whereas it’s possible in this prototype:


-A manned turret appears near the center of the upper platform in the final:


-S powerup instead of B; a grenadier appears at the edge of the upper right platform in the final:


-H powerup instead of C; C appears a bit ahead in the final:


-Another H powerup; no powerup appears here in the final:


-Special powerup instead of S:


-C powerup (partly obscured by foreground element) instead of M; also, the right side of the upper screen contains a short platform in the final:


-This gap before the stage boss appears much earlier in the final; here, the prior stretch of road is longer:


-In the final, there are no buildings in the background when the crustacean boss appears and during its battle:


-The enemy bikes are improperly colored. Also, the player cannot stand on the lower platform beneath the sacs that can be shot out, whereas they could in the final:


-After the boss’ death, the player is still on the jetbike (assuming they were on it when the boss is destroyed). In the final, the jetbike gets destroyed and the player runs on-foot:


Alien Hive (Tunnel 3):

-The stage is referred to as Tunnel 3 in this build.

-Both forms of the Laser gun shots appear green, likely due to a palette error:



-As with Tunnel 2, no powerups are provided in any of the corridors, whereas they are in some corridors in the final.

-The fireball launching eye turrets rise up from the ground in slightly different patterns than in the final. Sometimes, they move to a new position while protruding out of the ground. They also do not respawn. Their fireballs are harmless if the player ducks, while it is the opposite in the final.

-Ceiling crawlers lack their death animation while on the ceiling. They’re also (nearly) impossible to jump over when they drop down and run left/right.

-Targets, turrets and walls have simpler destruction animation; they also don’t explode. The turrets themselves have slightly different firing patterns. Destroyed eye target appear different from the final (as shown above).

-Destroying the core eye has no effect; as a consequence, the player is potentially stuck at the first screen (must press R to progress). The turrets cannot be damaged/destroyed:


-The 2nd corridor is different. It consists of 4 eye targets, instead of 3:


-Corridor 5 is significantly simpler, consisting of a single eye target and a few ground eye turrets:


The eye target will only begin opening periodically after all turrets are destroyed:


In the final, in addition to the ground turrets, there are 3 targets, as well as 2 wall turrets near the ceiling (1 at each corner).

-The 6th corridor is also simpler. It lacks the 2 wall turrets near the ceiling (1 at each corner) that are present in the final:


-Here, the aliens crawling on the ground from the holes appear and it is revealed that they were originally supposed to be Face Huggers. While their animation is slightly crude, the spriteset is complete, including the death animation:


-The 7th corridor is similar, except for additionally featuring 4 wall turrets, 1 at each corner:


When the large, main eye target is destroyed, no more aliens spawn. Like the 1st corridor, possibly linked to the presence of indestructible wall turrets, this section cannot be passed legitimately; it must be skipped by pressing R.

-As a consequence of not being able to properly destroy the wall in corridor 7, the boss battle does not begin. The heart, however, can be approached:


-At the battle, the ground lacks the holes from which eye turrets spawn, though this may be because the battle is not properly initiated. The lighting in this area is not dark and atmospheric, compared to the final.

-Overall, there is little to no lighting variation throughout the stage.

Harvest Yard (Black Viper):

-The stage is referred to as Black Viper in this build.

-The start transition effect for this stage differs based on which section is selected in the Debug Menu. The starting area has no transition effect; Post orifice, Crushing layer and Throat have the inverse of Harbor’s transition:


-The starting area contains the running brown aliens; in the final, save for gun powerups, this place is completely vacant:


-First powerup is an S instead of an H; another powerup is supposed to appear from the left as in the final, but it doesn’t until later:


-Just before the first Black Viper encounter, the powerup that was supposed to appear in the previous location (above) appears, having an L instead of an S. Also, at this point in the final, a third powerup should appear from the right, containing an F:


-The first Black Viper form takes very little damage to defeat and features no sound effects. It also contains simple AI; if hanging on the ceiling, it will keep switching between clinging on the ceiling and standing on the ground.

-After Black Viper mutates and stares at the player, it plays no sound effects and the screen doesn’t rattle from its roaring.

-After destroying Black Viper’s posterior segment, it doesn’t become transparent until the player grapples into it:


As a result, it is difficult to see the grapple point firsthand.

-Grapple points are strongly green:


-No eggs during the first main climb:


-Atop the first main climb, the section has a slightly different layout:


-No powerup shortly after the first main climb, whereas there is an M powerup in the final:


-This platform is much higher. The mouth’s cells are indestructible; they rapidly charge into the player. The mouth takes much less damage than in the final and has no death animation.


-M powerup instead of L; this powerup appears a bit earlier and in the upper screen, compared to the final. The vines above contain shimmy vines and much fewer climbing ones than in the final:


-H powerup instead of S; S should appear on the upper screen in the final, whereas the H appears on the lower screen. No eggs are on the upper platform, whereas they are in the final. The upper platform itself is much higher than in final. A mouth in the ground below the player in the final is absent in this version:


-Purple flying aliens appear as early as here, unlike in the final:


-Layout of the second main climb is much different and contains no eggs:


-Atop the second main climb, the upper path is the only path, unlike in the final:


-Purple running aliens appear as early as this section, spread throughout this leftward stretch:


-These 2 powerups are B and H. In the final, there is no upper path until a bit later; a C powerup appears from the upper screen much earlier and the B powerup appears on the upper screen, a bit later (shown below). There are no eggs on the upper path in this version:


-This section consists of more vines and a slightly different platform layout:


-C powerup instead of B; there are also more mouths (destroyed in the screenshot):


-The third main climb has no eggs, but purple flying aliens and brown running aliens from the right. The climb is somewhat shorter and has a slightly different layout:


-The top of the third climb is slightly tricky; the player must not climb the bottom-right vine or they will have no choice but to lose a life:


-The following rightward stretch has flying purple aliens. Eggs also first appear; they have no death animation; after being destroyed, they simply appear as follows:


-The entire following rightward stretch is significantly different, with upper and lower paths; also, there are hardly any powerup guns; so far only an M powerup appears (obscured by aliens):


-Notice the eggs in the ceiling:


-A Special appears shortly after (already picked up in the screenshot):


-Fourth main climb has no eggs and has a different layout/structure:


-Crushers are harmless and very short, not spanning the entire screen:


This segment is very different; it’s longer and has a different series of crushers, egg placements, etc. It’s also poorly designed, since the safe zones are too far apart, so the player will invariably wait under at least 1 crusher.

-Powerups are F and C, instead of S and C in the final; C powerup appears a few feet later in the final:

harvyardf harvyardc

-No eggs at the final section before the climb to the boss:


-The spinal slits are silent.

-The first phase of the final boss is completely different. As the platform rises to Black Viper’s head, the large eyeballs already attack the player:


So the eyeballs originally served a functional purpose, besides acting as a minor barrier; they attack in a sinuisoidal pattern.

In fact, the actual boss will not appear until both eyes are destroyed:


-When the boss lowers on-screen, its snake heads don’t yet spawn:


The player must first defeat a crudely colored brain form that appears multiple times:


They shoot projectiles in 8 cardinal directions, similar to one of the final version’s brain attack patterns.

The player must also survive a bouncing projectile attack:


Also required to cause the snake heads to spawn, the player must use the Laser Gun (as it’s the only gun that passes through all objects) on the protected brain.

-Snake heads are different in color and design:


When the snake heads retract, they hide completely in their holes, off-screen. Also notice the different grappling point below the boss’ chin.

-The snake heads have no death animation. They retract partially, exposing a grapple point:


-This version of Black Viper follows a much simpler pattern. After damaging the protected brain (main target) and the player is dropped off the grapple point, another snake head simply grows back. In the final version, the player must first survive and/or defeat 1 of 3 possible brain attack patterns before the snake head grows back.

-Every aspect of this boss battle lacks sound effects.

-Destroying Black Viper crashes the game, as the ending has not yet been coded.

Cerebrum (Gym):

The stage comprises plain brown tiles and a black background and is flat:


The player cannot pause the game. Absolutely no sound effects play. After the player moves to the right for a bit, the final boss appears. It is in this stage that the eyeballs are revealed to have an animation where they roll back to aim at the player:


The rest of the boss plays out the same way as in the Harvest Yard stage of this prototype:


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