NeverWinterNights Its, correct me if I'm wrong, a d20 based RPG/DnD type game that is possible of single and multiplayer scenarios.
More or less
It's an older CRPG (3 years old maybe?) that was based off of DND ruleset
It was designed as a single player game, but included the ability to set up a game online and run
some people through an adventure.
I don't know if it's a persistent world set up or not.
if it is I've been missing out..
NWN2 is essentially the same game with much better graphics.
The game engine (from what I've heard) while improved, is supposed to be kept largely intact.