“What games can I play with my Mac?”
The number of games available on the Mac is not as good as on Windows but its definitely getting better. Usually games come out for Windows first then the Mac version comes later.
Apple’s website has a nice list of games playable on the Mac, http://www.apple.com/games/.
For a comprehensive list of compatible Mac games check out the Wiki page here http://en.wikipedia.org/wiki/List_of_Macintosh_games.