Whats the difference between clicking New Campaign and New Module in single player?
New Campaign is where you can click to play through the original NWN2 Campaign, Mask of the Betrayer (1st expansion) and Storm of Zehir (2nd expansion). New Modules are adventures created by other people using the NWN2 toolset, which can be downloaded freely online. They can be found here: http://nwvault.ign.com/fms/TopRated….modulesenglish. Each module will have instructions on where to put the downloaded files so you can run it. They are also Peer rated, which can help when trying to figure out which ones to download. Modules give NWN2 almost endless re-playability.
