An implementation the classic arcade game Space Invaders with the following behavior:
- The tank (player's spaceship) moves right and left at the bottom of the screen when you press the arrow keys.
- The tank fires missiles straight up from its current position when you press the space bar.
- The invaders (enemy's spaceships) appears randomly along the top of the screen and move down on a straight vertical trajectory.
- When a missile hits an invader, it destroys it.
- When an invader reaches the bottom of the screen, the game is over.