The game could be controlled via mouse, keyboard, or (modified) Sega joypad to allow for extra functionality.
The plot is that your band of mercenaries have been picked from intergalactic 'non persons' and wanted criminals, and have been hired to shut down a mutation producing plant on an artificial planet called Graveyard.
The game was advanced for its time, allowing up to four player to play simultaneously. It was one of the earliest games to play from the three dimensional first person perspective, a style which was later popularized by Doom and Quake.