I was proud of myself for guessing the twist fairly quickly, but at the end, I saw that it was based on a short story: http://www.eastoftheweb.com/short-stori ... eWin.shtml and I have vague memories of reading that story in middle or high school. So it was more a matter of dredging up the twist in my memory than guessing it.
But nevertheless, very well made and indeed, Ravenloft-ish.