I'm not much of a gamer, but the ones I like, I'm addicted to.
Roller Coaster Tycoon - Create an amusement park, create rides (the best part), & try to keep the people happy.
Omikron/Quantic Dream - David Bowie provided music and helped create this game. Gain access to see Boz the Rider...who will you be when you die?
Diablo, Diablo II, Hellfire - Journey through the depths of Hell (been there, done that!) to help save a hapless town. Try Hellfire for new character classes and levels. I'm waiting on Diablo II, which has a release date of April 2000. Let's not hold our breath.
The Sims -I am completely addicted to this game. If only real life were this easy. Start families, fall in love, choose a career, move into your dream house. Once you try it, you'll be hooked.