Starbase Defense (Starbase Defence 64, and Astral Attack in Europe) is a single screen 1st person shooter where the alien race XENO have decided to attack our colonies by destroying the Energy Generators. You control a cross-hair and you must protect six generators on the bottom of the screen from the aliens in formation on the top of the screen. Each alien moves down the screen at different times and when they hit a line of energy they turn into a bomb which moves down the screen towards the generators. You can only shoot the aliens when they have turned into bombs and when they hit a generator then it is destroyed. When all the aliens have either been shot or hit the ground then they reappear but destroyed generators stay destroyed. It is game over when all the generators have been destroyed. The game allowed you to either use a joystick or a Stack Light Rifle to control the cross-hair but the re-release by Omega Software removed the option of the rifle.