Players control a tank which must collect the radiation packs scattered through various locations including forest, rocket pad, airport, bridge, and refinery. Players must also deal with enemies running around each location either by firing at them or memorizing their patterns so that they can be avoided. Ammunition is limited, but more can be gained by getting radiation packs. If …

Three days ago, a space ship landed near a small town in America, and the whole population of that town have vanished. Three agents were sent to investigate the alien craft, but not one of them returned safely. Electrical activity has been detected within the craft. The scientists discover that the aliens are preparing for something, but they don't know …