Real talk: whichever one makes you happy. Do a little research with some search terms such as "play {game} on Linux" and see what other users are running. Then, assemble a few live disks and test-pilot a few distros.

It's pretty fun getting to switch out your OS so freely and once you find an interface that feels good, you just plop your ass into that seat. If you keep decent records of your configs and such, you might find yourself starting over again multiple times while you "try to get it right." That's not failure, that's just advancing your skills and making yourself happy.

Linux can be as simple or as advanced as you want it to be.