Neverwinter Nights has potential, but nothing can truly hope to match up with a good pen and paper role playing session with some good friends, soft drinks, chips, and maybe a computer in the back for when people get bored of listening to the one guy who always draws out everything he does and tries to get all super-detailed and test everything for 20 minutes to everyone else's shagrin (me ^_^).
I voted sadness, because I personally can't think of anything more satisfying than seeing a major character sweat and bleed to save the world only to end up dead, or to have failed, or to see his loved one "sent to the next dimension" (Yes DBZ plug-in) by the arch-villain. Something about that extreme level of sadness and misfortune just makes the game that much more worth playing... for the sake of revenge. You just want to see your character reach out and grab that little spark of happiness that can only come from destroying the thing that took his life out from under him...
Anybody who has played Final Fantasy 6 (III) should remember how insanely depressing that game was, and at the same time, how ultimately kick ass the story line was. Everybody had something violently taken from them and they were all so lost in despair before they teamed up in a last ditch attempt to reclaim their planet, particularly Cyan. That's the way I like it.