http://store.steampowered.com/sub/4323/ It's available for Mac+PC. It's from 2005, so it probably runs in whatever computer you have. It's US$10 for the game with all the expansions, which is a freaking steal, because this game is absolutely addictive. Seriously. Buy this game. It's the price of a meal, and it's the best gaming deal ever. If they gave away Modern Warfare 2 it wouldn't be as much of a good deal as Civ IV complete for US$10.