Gamma-Attack

You are the commander of the only Gamma ship in this stellar field. The Vegan war fleet has taken control of your Gamma outpost planet and is defending it with Vegan laser pulse tanks. This planet is the only inhabitable planet in this star system, and you must stay there and fight the Vegans as long as you can.

Move your ship across the surface of the planet and destroy Vegan tanks that you encounter. Destroying all tanks advances the player to the next level. Each laser pulse that your Gamma ship receives reduces your hovering altitude. When your ship crashes, the "Gammy" appears and your game is over.

Trivia:

Most probably one of the rarest Atari 2600 games known to exist.

Only one copy known to exist. It was listed on eBay for $500,000 but never sold.

The flying saucer can be controlled while the game is in demo mode.

Notice that the alien (named GAMMY) that appears at the end of the game is also the company's logo mascotte.