The player controls the Guardian in human form while walking on Naju's surface, called the "Labyrinth". When in Naju, the Guardian turns into a spaceship in which the player can move around. The Guardian has a life meter that drops when hit by alien attacks. Players can pick up items to help fill the Guardian's life meter again. If the life meter runs out, then the Guardian dies, ending the game. The player can shoot at aliens with different types of weapons by pressing buttons on the gamepad. Players get different and better weapons during play.