You're a robot that's been dumped in an enemy zone, and it's full of murderous robots. Your aim is simple: survive as long as possible and cut down as many enemies as possible!
Use the left and right arrow keys to move around. Use A to jump and S to fire with your machine gun. Use D to hit. If you hold the down arrow simultaneously with S, you launch a rocket. If you do the same thing with D, you fire uninterruptedly.