I think I've made it fairly clear in the past that I don't see OpenBSD or FreeBSD as ideal gaming platforms (yet).
What these operating systems do well, they do exceptionally well.
Gaming - and in particular things like Steam - are another matter.
That being said, I think there's been a growing interest in getting these platforms to work well for gamers and surprisingly, there's a community of OpenBSD guys who are dedicated to gaming (check out this subreddit).
Anyway, there's a brilliant and exhaustive list of games and workarounds on Mr. Satterly's blog worth checking out (I was hoping to put together a list of my own but this guy has done such a fantastic job it saved me the bother!).
Most of it's retro and emulator stuff but he also covers some fun game engines.
I hope to test a few of these out and share my experiences here soon.