I played this game a few times at Howard's Department Store. It was 1981 or 1982 when I played it. It only gave two lives per game. Most arcade games gave three lives per game.
This game had five screens. They were called: Astro Battles, Laser Attack, Galaxians, Space Warp, and Flag Ship. Astro Battles was a Space Invaders clone.. But instead of having 55 Invaders, it had only 24. The four shields were replaced by a thin shield that spread all the way across at the center of the screen. The shield would disappear to let your lasers pass through it. If an Invader or Invaders reached the bottom of the screen, it wouldn't end the game like on Space Invaders. Instead it would take you to the next screen. Astro Battles was the only screen that Wasn't set in outer space.
Laser Attack was the 2nd screen. Most of the enemies on this screen couldn't shoot at you. But they did try to ram you. There were two or three of them that could fire at you. They shot out very long lasers.
Galaxians was the 3rd screen. It was of course a Galaxian clone. But instead of having 46 Galaxians, it only had 24. Space Warp was the Next Screen. It placed your ship at a Wormhole. You had to shoot ships that flew towards you.
Flag Ship was the fifth and final screen. You had to destroy a ship that moved back and forth across the top of the screen while firing at you. There was another thin shield that stretched all the away across at the center of the screen. But this time the shield wasn't there to protect you. It was there to protect the Flag Ship. When the Flag Ship was destroyed, it returned to the Astro Battles screen at a more difficult skill level.
Your ship could move left and right. It could also move up and down. It could move up to a third of the screen. This was one of the few arcade games that talked.
Gorf stood for: Galactic Orbiting Robot Force. This game was better than Space Invaders and Galaxian. It had both of those games in it and three more screens to boot. I give Gorf a 5 star rating.

I loved this game with all it's different challenges and cool computer voice that said "Gorf will get you" or something to that effect ...soooo cool. Plus you would get a ranking at the end like General or Corporal for your success or lack thereof. http://www.klov.com/game_detail.php?game_id=7983

Absolutely loved this game. Used to go play it on my lunch hour when I was working. I loved the way the game talked to you. Anyone rating this a 1 Bad move space cadet.