Take NWN1, update the graphics (but don't polish so it is buggy as hell) and suck out all the content and you have NWN2
As NWN aged and rumors of NWN2 appeared on the horizon it promised many things: mounted combat, more versatility, integration with the NWN user created content and more support for the multiplayer side of things.
It delivered none of this at all. In fact, I wish I had not got this game on release as they really didnt deserve my money. The game was completely riddled with bugs and obvious (and virtually game breaking) graphical errors which could not have been missed by a single tester during development.
More disappointing than this though was the fact that compared with NWN there is 0 content - less classes, less customisation, less items, less of everything you can think of. The years of work and content and customisation that the huge fanbase and community had put in was gone - worse than gone as the base stuff within the game was less as well. This was the main draw of the game for the vast majority of people and to take it all away is pretty much sacrilege.
So, in a nutshell - Take NWN1, update the graphics (but don't polish so it is buggy as hell) and suck out as much content and customisation as you can so it is but an empty shell of it's former self and you have NWN2