How about Blackjack. A while back, I played it for 8 hours straight, 9pm to 5am, at Star City Casino, Sydney Australia.
Man...some years ago I'd play video games all day (10 hours a day!). Played counterstrike, quake, UT, Wow, ragnarok, Generals, AOE & some more. Good times The only game I can play while being fully absorbed and interested anymore is Generals. I'm a big fan of the GTA series and looked forward to IV but it turned out to be shit.