There is a gap in ending level of SoU and starting level for HotU.
SoU and HotU are very loosely tied together. The SoU and HotU are not sequels of the OC, although they do make reference to some of the events in the OC. He also appears in HotU and can again be your henchman. The popular character of Deekin is introduced halfway into the SoU campaign and can be your henchman. It is generally considered a mediocre campaign.
OC stands for Original (or Official) Campaign and refers to the campaign that came with the original release of NWN, the story involving the much discussed Aribeth. To play a premium mod purchased through the BioWare Store requires an on-line verification just like attempting a multiplayer game. The newest premium mod Pirates of the Sword Coast is still only available by download. NWN Kingmaker 'expansion' bundles Kingmaker, ShadowGaurd, and Witch's Wake remake on CD. NWN Diamond edition bundles NWN, SoU, HotU, and 3 of the 4 current premium mods: Kingmaker, ShadowGaurd, Witch's Wake remake and is only DVD. NWN Platinum edition bundles NWN, SoU and HotU and is either CD or DVD. NWN had two expansion packs, first Shadow of Undrentide (SoU), then Hordes of the Underdark (HotU).
