You are a plant and need to defeat the aliens in each level of this game. You have a limited amount of shots. Sometimes you may need to shoot some dynamite to get to the aliens. Other times the aliens will be wearing armor and those aliens have to be shot twice to die. The first shot will destroy the armor. The ammo that you shoot bounces around and can kill multiple times before it disappears but you have to shoot it just right. Aim is very important in some levels because the aliens can be above you on an impenetrable stage.