User Summary Earth has been taken over by aliens! All military forces are under their complete control... except you. The last vestiges of Earth's defenses are still under your control and you must make prudent use of them. You will have to engage enemy forces, both alien and domestic. You will have ample opportunities to upgrade your firepower, but you must avoid coming into contact with aliens and/or enemy bullets. All is not lost. You have eight levels to prove it.