NwN is a game that you can play multiplayer but your just as well off doing single player stuff. The thing about NwN and it's sequel is that they both have VERY robust mod tools that people use to create their own modules and games and campaigns. If you're just going for the vanilla game, probably you're better off picking up the sequel as the Campaign is much better written in my opinion. NwN1 has alot of running around and moves at a snails pace. NwN2 is much faster paced than that and you can breeze through the single players prologue and first chapter in 1/10th the time of NwN1.
As to Baldurs Gate, the RPG series used what's known as the "infinite engine" which was also used in Planetscape Torment, Icewind Dale (good luck finding those) and I think a heavily modified version was used for the Fallout series. Currently the developers from Black Island have moved and are now Obsidian Entertainment (who made NwN2, it's expansions, Knights of the Old Republic 2, and are working on a Spy and Aliens RPGs). If you like Strategy games one suggestion I would have (this'll have you looking everywhere) is called Myth. This was a series primairly for the Mac's back in the day by of all people Bungie of halo fame. The basic concept is one that few have replicated, you start with a set amount of units these units will be the only ones you receive (usually) and will gain experience. It's fantastic fun and loosely based off the "Black Company" books by Glenn Cook. Also another one you might try would be Civilization IV, basic premise is you lead a tribe of people (you pick from historically powerful nations) from the stone age to the information age and dominate your opponents via military, culture, or other strengths. There isn't much management in the battles themselves, however this does force you to change your economy to support an offensive and such.
