Destroy the invaders spaceships before they destroy yours. There will be 3 waves for you to defeat. Stalemates will be repeated to determine the victor.
Place you spaceships by tapping the start and end positions of each spaceship, or use the Auto to randomly place them.
Once all of your spaceships have been placed, set targets that you wish to attack manually or with Auto. Auto will fill remaining targets if some are already placed. You get one target for each of you remaining spaceships, except on the final wave.