Some enemies have the ability to morph into new enemy types with different attack patterns, with one even taking the form of the Galaxian Flagship. Stages are indicated by emblems located at the bottom-right of the screen. Enemies become more aggressive as the game progresses, increasing their number of projectiles and diving down at a faster rate. The third stage and every fourth thereafter is a bonus stage, where the aliens fly in a pre-set formation without firing at the player.