Planetary Defense is a space strategy game where you take charge of a planets defenses against waves of attacking aliens. Defend against missiles, multiple warhead rockets, cloaked starships, meteors, homing missiles and laser-armed satellites. Planetary Defense is a space strategy game where you take charge of a planets defenses against waves of attacking aliens. Defend against missiles, multiple warhead rockets, cloaked starships, meteors, homing missiles and laser-armed satellites. Some of the 21 missions include orbiting moons complete with colonies, defensive shield grids, radar bases and evacuating starships. Superb graphics and low system requirements, only a 3MB download. High score table, 3 Difficulty levels and a variable game speed for hours and hours of space-blasting fun!