I was just about to set up ErsatzTV for this exact thing, but the maintainer announced recently that he’s not updating it anymore and nobody is taking over. It’s probably fine for now, but I’m hesitant to start running it. He’s encouraging forks, but none are really the clear successor yet as far as I know. I don’t know if there’s anything else comparable.

I have a MacBook that I use opportunistically for games. It’s not my primary gaming machine, but I keep Steam on it for if I’m on a work trip and have some down time or whatever. I imagine a lot of the Mac users in the survey are in the same boat.