Years ago when I was in college there were a few games for the Mac that were quite cool. One of them was Solarian II. It was kind of like Galaxian with really cool sounds. Thankfully, it's now been ported to OS X and it's just as frustratingly cool as it was back then. I think I may even cough up the $10 for it once I get done with the trial runs.
Now, we just need are new ports of Arashi, Crystal Quest, Shufflepuck Cafe (remember the opponent who'd get drunk as he lost?) and Airborn (Hopefully I can find links to old pages with pictures of these). Now that I think of it, there were a ton of really simple fun games for the Mac back then. I remember the little DA version of Tetris that I'd waste hours playing when I was working in the computer lab.
