I remember a 3 headed serpent in A1200 Gloom well technically a dragon but I was shooting at it like 26 years ago roughly, probably earlier than that. Gloom did have maps on CD32 that weren't on A1200, think I saw an Aztec level in Amiga format
Fun game, technically impressive but AB3D2 and it's sequel were my fave Amiga FPS - Doom 1, 2 and Final also, but AB3D was a nice change.