Note that "addicting" does not necessarily mean "good." I'm just talking about games that make it hard to stop playing. For me, it'd be Fallout 3, though that wasn't entirly true until I realized that headshots would sometimes actually decapitate people rather then simply make their heads explode. The entire population of Megaton 27 times over later, and I still can't stop watching slow-motion decapitations. I have a problem.