Shadows of Undrentide isn't a conventional expansion pack, because it's not a continuation of the previous game. Essentially it's a brand-new campaign using the same engine, so although you're required to install it on top of Neverwinter Nights, the stories of the games are completely separate. Undrentide's campaign is shorter than that of Neverwinter Nights, but that doesn't mean it's short--it will probably last you 25 to 30 hours, and there's some good replay value to boot. The expansion retains the same excellent mechanics of Neverwinter Nights, so you can easily control your character and access a variety of useful in-game information using the mouse and a few keystrokes.​