Protect your planet from outer space invaders! You are the tiny blue alien at the bottom of the screen in each level. Descending lines of invaders come from the top of the screen. Look for walls at the bottom of the screen, because hiding behind them can save your health and keep you from getting hit. To move your character, use the left and right arrow keys to move left and right. Push the up key to shoot at the invaders. Don't hide behind a wall for too long. The invaders will shoot at it and weaken it. Eventually, they will destroy it!