Galaga

Move your fighter ship left and right using the arrow keys and press Space to fire. Alien formations appear at the top and attack in swooping dive patterns. Destroy all aliens in a wave to advance. The boss aliens (green) can capture your ship with a tractor beam — but if you destroy the boss while it holds your ship, your ship returns and you get a powerful dual-fighter setup with double firepower. Bonus stages appear every few levels — destroy all aliens in formation for maximum points. Master the alien attack patterns to survive.