If I remember, the premise was that you had to go up a mountain to confront a fox goddess or demon, maybe a kitsune or something. May have had 'Nine-Tailed' in the title. It wasn't really a game, just a small collection of sex scenes that were rendered in 3dcg. I believe the artist had another release as well that was just another collection of animated scenes. The renders and animation were realistic with dark nigh time lighting in an outdoor setting. I don't think they're on this site anymore, as none of my searches are pulling it up. I remember seeing it maybe three or four years ago.