An in-game menu allows a variety of gameplay changes. The player may toggle the shield option on or off. If activated, "shield" mode allowed a player to press down on the joystick to become invincible for a short period (only one shield was allotted per level). "Time warp" allows the player to press up on the joystick to temporarily slow the enemies. The type of shot fired can be changed by activating the "penetrating fire" option (which enhances the beam fired so that it can hit two mutants rather than one) and/or the "guided fire" option (which causes the beam to be moved with the joystick rather than firing in a straight line).
