Deep within a vast underground weapons complex known as Force Valley, one faction of humans tries to gain the upper hand by creating super-enhanced cyborgs. One of their experimental cyborgs, Magin, escapes and creates an army of enhanced weaponic monsters, turning Force Valley into a Metal Dungeon. Players must assemble their teams to plunge into the depths and root out the monsters. Players choose from five character types--fencer, striker, analyzer, caster, and broader--for building their teams, which may be further enhanced by finding or buying chips and implanting them into characters. Players can add to their team by finding and reanimating the corpses of fallen warriors and transforming them into one of five unlockable character classes. Metal Dungeon can be played by a single player (who may control up to six characters) or by multiple players each controlling their own character and their actions simultaneously.