Godkaiser Hell, a Bio-Beast, formed an army called the Steelmask Force and has reigned supreme over Earth since a nuclear and biological holocaust disfigured most of the population. The survivors fled underground to escape the Bio-Beast horde. You take control of a Mazinger-Z in an attempt to reclaim the Earth.

The gameplay is a hack-n-slash game, where the player controls the suit by using the D-pad and using the face buttons to slash at enemy monsters. There is also a Super Attack that the player can use, but it will decrease their health after each use. The enemies consist of mutant animals such as dogs and beetles as well as the Bio-Beast soldiers that can range from regular soldiers, female fighters and even ninjas.

There are five levels in all (Tokyo, Asia, Europe, New York and Egypt) divided into three stages with a mini-boss and a main boss the player must defeat to advance to the next level. There are also items scattered throughout the levels that will give the player extra points, health refills, an extra life and even a brief stint of invincibility.