When playing Rengoku, the player assumes control of an android known as A.D.A.M. (Autonomous Dueling Armed Machine), who, along with his fellow androids, was created by mankind for the purposes of war. However, once peace is achieved, the androids are placed in a tower known as Purgatory, where they compete in a series of battles similar to those seen in gladiator games.
When the humans discover that the A.D.A.M. that the player controls has developed an electronic soul and is attempting to flee, they let loose all of the other androids in the tower with the directive to kill him and destroy his electronic soul. The gameplay is mostly a shooting game, with some role-playing game (RPG) features thrown in for good measure. There are multiple levels to accomplish, each of which becomes increasingly difficult and adds more androids to eliminate. If you eliminate enough androids, the android will get more powerful and have the opportunity to modify its armament.
Beginning with bare hands and ultimately upgrading to weapons, however unlike other games, the guns are mounted to the android himself, giving it the capacity to have weapons coming from any part of its body, including its hands, arms, legs, and even its forehead, and giving it the ability to employ multiple weapons at the same time.