Don't let the evil aliens reach your base so better zap them all, don't even leave a single one alive! Survive the hordes of unearthly creatures that will come your way. Shoot down that one-eyed blue alien carrying a red box which has some bonus/power-ups inside that will help you prolong your battle. Hit some astronauts along your way to increase the score multiplier. The higher your score the bigger the chances for your name to be listed up in the leaderboard!