Use the left and right arrow keys to move your spaceship.

Press the spacebar to shoot missiles at the aliens.

Press the up arrow key to use a super weapon and destroy all aliens on the screen.

You lose a life if an alien reaches the bottom of the screen or if you are hit by an alien missile.

The game ends when you run out of lives.

Your score increases when you destroy an alien.

You are awarded a super weapon every time your score increases by 300 points.