The player controls a spaceship that moves horizontally at the bottom of the screen, firing upward. Enemies, typically one of two types of birds, appear on the screen above the player's ship, shooting at it and periodically diving towards it in an attempt to crash into it. The ship is equipped with a shield that can be used to zap any of the alien creatures that attempt to crash into the spaceship. The player cannot move while the shield is active and must wait approximately five seconds before using it again.
The player starts with three. Each level has five separate rounds. The player must complete a round to advance to the next.