The majority of enemies are spaceships, which must be destroyed to complete a level. They appear either from the centre of the screen or from one of the edges, and move in swirling patterns. They can shoot the player's ship or destroy it by contact. They hover near the centre of the screen after completing their deployment pattern, and occasionally fly outwards and shoot at the player. If not destroyed by the player, the enemy ships gradually fly away one by one. There are also several other types of enemies: satellites, asteroids, and laser beam generators. These appear intermittently and soon disappear of their own accord if not destroyed by the player. After completing Earth's bonus stage, the player must travel through the very fast "3 WARPS TO NEPTUNE" level before returning to the start of the game.