Parvateshwar: I remember playing Nintendo games as a little kid and having the best time with Donkey Kong and Mario, I still enjoy them now but they weren't as fun as when I was 6. In terms of modern games I would have to say WoW, HOWEVER it's only fun if you have a lot of real friends with whom to play. If you're playing solo it's like being tossed into amateur hour and having to put up with complete assholes while sinking further and further into addiction. So I will have to go with the Baldur's Gate series as my favourite games that don't involve sacrificing your life and that isn't coated with nostalgia.
I enjoy WoW solo myself which allows me to avoid most of the "complete assholes" you mention. The solo exploring, questing, crafting, AH/money making aspects of the game are fun particularly when you'd like to play an MMO on a sane schedule that allows time for other games and other interests, like having a real life. ;-)