To be honest, I don't think I've played one Atari game. But I'm sure I've played games of that retro style, though I can't recall any of the unobvious (obvious being pacman, pong, tetris, etc..) ones by name.
Combat & Asteroids are my two "cream of the crop" favorites.
...other Atari 2600 games I played and really liked, include: Space Invaders, Missile Command, Yar's Revenge, H.E.R.O., Phoenix, Pitfall, Circus, Warlords, Adventure, Defender II.
Jr. PacMan. One of the best (if not the best) games for the Atari 2600 and definately one of the hardest (if not the hardest) games for it also. If you don't believe me about being hard, just try to clear the entire first maze with all four ghosts active. 'Bet you, you can't. Try it and you'll see what I mean.