Grand Theft Auto: Vice City
that game made me an addict) i played it all night long. all day, every day... why? this is the only game of all, that waked me up in the middle of the night, just to think about what i can do there) none of other games did that to me, and i played tons of great games.. but this is the one. the second one that affected me (not that high, but still), was
Call of Cthulhu: The Dark Corners of the Earth.
i even tried to write a book about similar stuff, but with funny things and jokes. but after a few pages, dropped it.