Orbitron

Orbitron is a single screen shooter where you are the last fighter pilot left to protect your planet, Hyperion from an alien invasion over various levels. You start on the bottom of the screen and you can move in various directions as the aliens appear and you must shoot or avoid them. If you are shot or hit an alien then you lose one of three lives. After a certain amount of aliens have been destroyed then you move to the next level and different types of aliens.