You are a pilot of a space craft whose mission is to accompany and guard a huge Mothership leaving Earth on it's way to another galaxy. As the Mothership leaves Earth's orbit an invasion fleet arrives to destroy Earth and it is now your new mission to protect Earth from this invading force. The game is split into three parts and you must destroy all the craft around the hull of the Mothership, then navigate through a tunnel to get to the aliens HQ before finally rendering the base itself useless. The first part of the game is a multiple scrolling top down shooter where the screen scrolls when you move. Below the playing area is a radar showing you the location of all the alien crafts and you must shoot them all with your laser while avoiding touching the crafts, their bullets and the sides of the hull. Either side of the radar is a green square and when you are hit a few times it changes to amber, then red before your craft is destroyed. Destroy all the ships and you face a large boss which needs multiple shots to destroy. The second part is viewed from the side with the screen scrolling constantly from right to left. You must navigate through a tunnel avoiding touching the walls or your ship is destroyed. As you travel further through the tunnel your speed gets faster until your speed then slows down again. The final part of the game is a maze type game where you must walk about on foot searching for stars while avoiding the robots that guard the HQ. Once you have collected enough stars then the base cannot be used any more.