Heavy Unit (Arcade)
Heavy Unit is an R-Type-type game with a transformation gimmick. The titular "Heavy Unit" can switch between a smaller to hit but offensively weaker ship form, and a bulkier and more powerful mech form.
There are two hidden credits in the game ROMs. The first is in the main CPU at address 0x68:
To-Y 68K Original Program
S. "To-Y" Igarashi is listed in the credits in the software section. Note that the game runs off three Z80 cpus, so it was apparently converted from a 68K source.
The other message is in the slave CPU, starting at 0x9:
Heavy Unit Programmed by Y.Yamauchi System Codineiter F.Komori
Y. "Uai" Yamauchi is also in the sofware section of the credits, but F.Komori is mysteriously absent.
This is what looks like an earlier shield animation for the ship-type Heavy Unit. In the final game, the ship just uses a scale-down version of the robot-type's shield. One of the shield frames is cut off at the bottom, so there might have been other frames for this animation that were overwritten by other tiles.
These are two alternate designs of the pellet-shooting orbs found throughout the game.
An odd-looking enemy (But they all are, really), this seems to be a beetle with a human-like face and a cannon on its back. The palette for this enemy is loading at the transition from Scene 2-1 to Scene 2-2.
So it turns out that those red things in bubbles at the end of Scene 2 are actually embryos. This animation shows one quickly developing into a fish monster which has its own unique death animation. In the final game, the animation is frozen at the first frame.
Part of an unused concept for the wasp enemies in Scene 3. It looks like three different looking rocks would fall down from the ceiling, with one of the rocks being the wasp in disguise. The wasp robot would quickly transform and attack the player.
This grotesque hulking mess of a boss got pretty far into development, but doesn't seem to have been coded. Its palette is loaded during Scene 4, so that's probably where it would have appeared before it was replaced by Hard Shell II.
It's made of four separate objects: The body, the hand, the lightsaber / sword, and what seems to be a shoulder part. There are also small projectiles that match the angle and color of the sword.
Here's a mockup of how it would look properly assembled. It's very likely that at least part of the body's sprite would be off-screen, since the entire sprite matches the resolution of the screen (256 x 224) exactly.
It's a shame this was cut, since there was clearly a lot of work put into it, but that's one of the perils of game design, one supposes.
|1B||Only four and a half seconds of this track normally play in the game. The entire track is eleven seconds long, and it loops too.|
|2B||A downbeat, looping forty second track that probably would have been used as a piece of stage music.|
|63||A short but victorious tune that doesn't really fit in anywhere in the final game.|
|6B||This version of Scene 5-1's track has a short three second intro that's never heard in the game proper.|
|70||This seems like a more upbeat Game Over track.|
|74||And this could well be an unused Continue theme. In the actual game, no music plays on the continue screen.|
|89||This simple percussion loop was probably used to test the game's sound engine.|
|The Heavy Unit series|
|Genesis||Heavy Unit: Mega Drive Special|