I don't think there are a huge number of Steam games running on .NET, but the number might be increasing due to the rise of Unity. Many, many games are written

I don't think there are a huge number of Steam games running on .NET, but the number might be increasing due to the rise of Unity. Many, many games are written in C++ and require reasonable porting efforts to get to Linux support. Someone like Ryan C Gordon (icculus) is much better qualified to comment on that, though. I doubt Microsoft would ever port DirectX to Linux, but then again I doubted they'd do that with .NET, and look where we are. The DirectX->Wine code works pretty well, but it's always going to be behind the state of the art.