Single Player RPGS Aimed At Adults

Fallout, FALLOUT FALLOUT! Seriously, get it.

gothic 1 and 2 are very good single player rpgs that are aimed at adults

too bad your having trouble with bloodlines, its a very good game imo

also the 1st vampire game is supposed to be good though i havent played it

If you have a PS2, I'd recommend the Shin Megami Tensei series, particularly Digital Devil Saga 1 and 2. Good story, and its a fairly mature RPG: