Gaming is as old as computing itself (really!) and it's still one of the most important aspects of computing, what drives fast interactive graphics hardware and software development. As a gamer, I'm just going to say this: Gaming is important.
The following is by no means a comprehensive guide in "getting started gaming on Linux", it's just my 2 cents.
Describing the hoops I'm jumping through (and not jumping through) to run the games that I want on Linux. So, maybe this will help you, maybe it won't.
Games I play, and how
Again, this is not a list of the games you can play it's the list of the games I play, and how.
Creeper World 3
Day of Defeat: Source
The Final Station
Earthworm Jim GOG.com
Diablo 1 Win 98 on VirtualBox (because IPX)
Diablo 2 Play on Linux (WINE) + nGlide for 3Dfx
Carmageddon 2 Same as Diablo 2
Beasts N Bumpkins dosbox
Duke Nukem 3D dosbox
Soldier of Fortune Still working on audiofix. Actual native WinXP box..