Earthworm Jim (SNES)

A Lumbricus terrestris in a robotic suit faces off against the likes of a mad scientist with a simian fused into his crown, an alien made of snot, and a hideous queen with a gigantic gastropod mollusc for buttocks.

It could only be Earthworm Jim, or perhaps one of its sequels...

Unused Graphics
Graphics, a tilemap, and palette exist in the ROM for a "Licensed by Nintendo" screen. Since the graphics are the first thing loaded in VRAM during several of the opening screens, and the Genesis version has a similar SEGA logo screen, this was likely intended to be the first thing shown upon startup.

There is also enough black space below the logo for the animation of Jim flexing. The animation was moved to the copyright disclaimer, which is actually the first screen to appear in the final version.

Cheat Mode
Dl6xbD_dxaQ During gameplay, pause and press Left + A, B, X, A, A, B, X, A, Start. A screen showing the Shiny Entertainment staff will appear, followed by the debug menu.

Unused Cheat Codes
Pause the game and press A, B, X, Y, Y, X, B, A. The code seemingly does nothing; its purpose may have been "Suicide", a cheat code found in the sequel and included in the PlayStation and Saturn versions.

FTDtMfDYQsQ Pausing and entering Y, A, B, B, A, Y, A, B triggers a weird sequence in which a message for Nick Jones, one of the game's programmers, is displayed, informing "him" that this is the "old cheat code".