Demon Attack is one you don't hear about too much anymore, but this is a great game. If you like Space Invaders, or Galaga, or Galaxian, or any of that style of game, I think this is one of the best ones. Especially on the Atari, it seems smoother. The graphics, for whatever reason, actually seem a little sharper. And the gameplay is unique compared to those other games, because you can see on the screen the motion of the demon things that are attacking you. It makes them quite challenging to hit.

And you hit them and they split into two and it just keeps going from there. Of course, it's the Atari 2600.

This is one you can easily find in a bulk lot on eBay somewhere, and I highly recommend Demon Attack if you're bringing back the old school Atari.

And note that it has one or two players. So it's a good party game because you break this one out. Most people think it's Space Invaders, but upon closer inspection, it's Demon Attack.