you can game on linux, just not very many of them
doom(all of them), matter of fact doom3 came out for linux well before OS X
soldier of fortune
alpha centauri
counterstrike(I think)
x-plane
civilization call to power
about 20 other titles,most run in openGL
best way to do this is just get another machine and learn it a little at a time, you dont need anything expensive or particularly fast, heck, it runs fine on a p200 with 128mb of ram and a 4-6GB HD, of course to do anything intensive you need more, but you can learn all of it on a slow cheap machine
windows has its place, but once youve worked with linux for awhile, its hard to use windows and not laugh hysterically at it, windows is a toy compared to linux
I know people on the hardware forum have to be really puzzled or pissed at some of my comments about windows, for example, guess what, in linux, there's no defragging, EVER, linux filesystems dont need it.There's a whole bunch of things about linux that are like that too, linux is an OS made by geeks,for geeks, so, it may be a little weird at first, but it makes sense very quickly once you get used to how literal and direct it really is.Another benefit is its unix based, so learning linux is also learning unix,OS X, freeBSD, and any of the POSIX compliant OS's.
Its for your own growth young man, give it a shot.I kow what its like to be into games, been there done that, spent thousands of $$ on it.At some point though, games get tired, and sometimes you just wanna get things done quickly without having to worry if its gonna work, no more crashes, and you can load the machine down with apps, and it just slows down a bit and keeps chugging along.
The one thing Ive found that linux doesnt really have an equal is video, nothing else even comes close, for playback, editing, encoding, decoding, whatever, it may not be all point and click, but I havent found anything even close to what I can do with it versus others, and the software is FREE.