Out of curiosity, is there a reason you don't just dual-boot Windows for games?
I love and use *nix every day at work, but for gaming, if you're just going to open Steam and launch into Divinity anyway, why does the underlying OS matter at all?
I assume that is a very personal choice for most non-Windows user so here is only my point on that:
a) Most of my machines don't even have Windows installed so it takes a bit more effort than just rebooting.
b) Ethical reasons - You can insert any reason on free software (free as in freedom not as in free beer) here.
c) The one copy of windows that I have installed is always outdated and needs 1-2 hours of patching before I can play seriously
d) If I boot windows I am limited to only gaming because there is literally nothing else installed in my windows system. Also, I can't have any "serious" tasks running while gaming.
