BioMetal is a fast-paced, side-scrolling shooter game. The war that divided the galaxy and used all its resources has ended. A fleet was sent on a mission to find more natural resources. They never returned. Their last transmission reveals that the enemy created one last experiment - a combination of the aggressive nature of animals and the efficiency of machines named BioMetal.

The MF-92GX Halbard mothership has been assigned to destroy the threat. The player is piloting the MF-92GX Halbard fighter that is equipped with the experimental Gel Analog Mutant weapon. The GAM's power is charged up while not in use, and can be used to surround the ship as a protective shield or be thrown at the enemy forces. It slowly drains charge energy, and the pilot must balance being protected by the shield with recharging. Their are three choices each for primary and secondary weaponry, including plasma shots, lasers, and missiles. The enemies become larger, more aggressive, and more plentiful as the game progresses.