I have two words, "Lone Wolf".... although technically for teens, it does have some very violent themes in many of its books (so its probably as close as you can get). Also, it is probably the best Choose Your Own Adventure series ever writen (At least book 4 and after.... the first 3 books are OK, but unless you have a very good imagination they can be pretty dry), there are about 28 books in the series.
Its based on a D20 system, and has character design (which many choose your own adventure books lack).... the abilities you choose for your character play a role in which choices you can make. Do you want to have a sixth sense for danger and never fall into abushes, or be able to blast your oponents mind with telepahy and improve you combat effectivness. Everytime you finish a book in the series your character "levels up" and gains a new ability.
Its a fantasy genre.
Anyway... check it out.
Also.... you can download many of the books for free (apparently) at this website.