The sweet dungeon crawler Bastion, has been available on PC and Xbox 360 a while now, but a new platform has just been added to the mix - Google's Chrome Web Store.
It's really simple, if you're using Chrome you can play the game right there in the browser. All it takes is a 40 megabyte installation, and you can even try out the game for free.
Chrome makes use of cloud saving so your progress in the game is saved regardless of where you're playing, and naturally this also means you can play Bastion on your Mac.