The aliens have invaded the planet Earth, and the only hope left to stop them is you! Join the action now is this simple but challenging game and stop the menacing invaders here at Green Terror. There's a stationed alien in each level and you must knock them down with the help of your cannon. Adjust your cannon's power and aim for the enemy. You must also watch carefully for there will be soldiers too hanging around. If you hit them, you will fail the level. Magnets can change your shot's trajectory, and can either repel or pull your cannonballs.