I don't know of any and I wouldn't be surprised if there aren't any decent ones. In a prerendered game, a single image can take hours to render, so it would be so time-consuming to render every variation of a player character in every scene they appear in.
I could see it being easier to implement into a real-time game like The Twist, but since that's an incest game, the PC's family would have to change if your skin colour or whatever.