Mankind has spread throughout the solar system into vast colonies, which are under alien threat. The bad guys have anti-matter machines capable of destroying the planets' power source. You must destroy these before they can reach Critical Mass. Your journey involves travelling primarily to the east, in a hovering craft. It is rotated with left and right movements, and accelerated with forward motion. Laser and shield strength are limited and monitored on screen. Use them wisely, as hostile aliens and mines line the route. Get shot down and you re-emerge with a jet pack, now directed to the bay which can give you a new craft. The force-field gates near the power planets are guarded by turrets which must be shot down. The mission then boils down the insides of the plant, which must be destroyed before its tractor beam has sucked you into the core.