Summary: After the evil invasion on Deimos & Phobos was averted by the Marine hero, only a few of the demons still lingered within the abandoned halls and complexes on the two moons of Mars. As a last-ditch effort, the military and the Union Aerospace Corporation decided to bombard the moons with extreme radiation in hope of killing off any remaining abominations.
A single, mysterious entity, possessing the ability to resurrect any dead demon it came across, survived the exposure. It slipped past the military's sensors undetected and recreated the entire demonic horde - now they are stronger, more vicious than ever before and invade Earth to spread chaos and death! All Marines of the strike force, which was sent to contain the advancing armies of hell, were mercilessly slaughtered within moments - except you! As the last man standing, your mission is clear - prevent the destruction of the planet, exterminate all the demons and send them back to hell!