Yup, I used to use FreeBSD and it worked okay. When I used it, the Nvidia drivers were better than AMD, but I don't know if the FOSS AMD drivers have been ported to FreeBSD.
You can theoretically run Linux programs (such as Steam) on the BSDs. And I am pretty sure that there are some open source games on BSD too. Only tried it a few times tho.
Edit: and there's a WINE version for FreeBSD aswell.