What I do for a living is somewhat like mercenary prostitution... I spend a lot of energy trying to find games to bring to alternate platforms, like … - Ryan C. Gordon

I find if you're targeting Windows, Linux, and Mac OS X right from the start, your code will probably work anywhere else that you might try it later... Writing code that is cross-platform from the start requires more discipline, but I find it is worth the effort.

I happen to like the "feel" of OpenGL more, which isn't something I can explain well to those that aren't programmers, but I don't think it matters much at this point which API one chooses. More or less, you have feature parity between both APIs, both have made a handful of design mistakes, and both do a few things in slightly more pleasant ways than the other. Of course, the unforgivable thing about Direct3D is that it only works on Windows. If it was truly cross-platform, though, I wouldn't really object to using it. But since you write OpenGL almost everywhere, and Direct3D almost nowhere, it seems like a false choice to me.

Video games are sexy. People need to be aware that GNU/Linux is more than just something to drive your webservers... A lot of people (myself included) feel that video games are a major factor in getting GNU/Linux to the masses. I can't count the number of people that have said, "Thanks for porting [GAME X]! It was the only reason I kept a Windows partition around!"