When I only had a Mac I games like crazy on it, and it was good anyways since the Mac was a superior platform back then (I'm talking mid 90's or so) I mean you actually had a desktop GUI and no PC game had graphics like the Marathon Trilogy.
But then on 2000 I got a PC and realized that Macs were no longer superior for gaming in ANY sense, games on PC are cheaper, PCs are cheaper for performance, games run better on Windows, they have more features on Windows and they are usually much more flexible on Windows.
So now I do gaming almost exclusively on Windows, I still play some games on my Macs though, namely Warcraft 3 and Marathon (yes I know there is A1 for Windows but it just feels wrong playing Marathon on a PC). The thing there is not as much variety for Mac games as there is for PC games and since PC games are better in the first place, why bother? The only advantage of Mac games is the convenience of not having to switch computer/reboot to bootcamp.