Vicious predators from the far ends of the universe are invading our planet! They’re mean and wicked, creating havoc everywhere they go! Time for the aptly named “Alien Busters” to take control: Karen (absent in the Master System version, named "Karla" in some versions), Garth (named "Gordon" in some versions) and Scooter (the robot, named "Slammer" in Master System and PAL versions). Get nasty and kick some serious martian butt!