Hmmm... I haven't done anything like this since the 90s, when you would just run without an OS, using the VESA standard for graphics (sound was trickier). If I had to do something like this these days, my first thought would be to make a custom Linux distribution that only runs the game. Arch Linux seems like a good place to start.
Although using Linux might not be an option due to the GPL if this is a commercial venture. FreeBSD would be a better choice from a commercial point of view.