Linux is good for gaming, depending on your preference. Mainstream games are build for Windows and DirectX of course but for a OS that supposed to have 1% desktop share, it has a good amount of games, plus WINE.
Linux relies on the good will of game developers and there is not that many big time ones that have any good will now days. Linux got the Quake games thanks to idsoftware and Epic gave us UT in till 2004. I'd say that's good going for purely goodwill.
Small studios make Linux games and make a little profit, it's been proven, so there is hope. Though you have to say, Windows users get suckered buying the same crap, year in, year out and bad console ports, cough* EA, Infinity Ward, Rockstar * cough.