MazinSaga is a brawler based on the manga of the same name by mangaka Go Nagai, and is a spin-off of his larger Mazinger Z franchise about the titular enormous pilotable mecha. It was released in all territories: in Japan, it was released by Sega as MazinSaga; in North America, it was published by Vic Tokai as Mazin Saga: Mutant Fighter; and in Europe it was published by Sega as Mazin Wars. The story of the game concerns the alien Biobeasts which take over the Earth and push the human race underground. Using the Mazinger Z suit, Dr. Koji Kabuto takes the fight back to the invaders.
The goal of each stage is to fight through henchmen as a normal-sized version of Mazinger Z before growing to colossal size to fight its kaiju boss. The stage's boss will occasionally appear as an enormous stage hazard prior to the showdown. The finale has Mazinger Z fight all the bosses again in a boss rush before taking on the leader of the Biobeasts, Hell Mazinger, in a final battle.