The recent nuclear, biochemical warfare has left the Earth's ecosystem spinning out of control, but the environment is not the only victim, nor is it the only unbalanced bi-product of the grilsy war. All surviving Earth inhabitants have been forced to live beneath the planet in an underground enclave. Meanwhile, every creature that walks the earth or flies its murky skies is a ghastly biological horror, and an integral part of the army of armored biobeasts who for the Steelmask Force.

Earth is not a pretty planet in this year 1999, but you and all-world hero, Mazinger-Z, might be just what it needs to clean up the mutant scum of the Steelmask Force. Look Garada-K7 dead in the eye as you fight him hand-to-hand in the streets of Tokyo. Slug it out in India in slime-infested catacombs. Fight a mutated dinosaur on the plains of Spain, giant bugs in the concrete jungle of New York, and a horrible familiar for in Egypt before going on to the ultimate battle with the most hellacious challenge of all.