While the original campaign told a story written and paced for teenage gamers, Mask of the Betrayer is better suited to more mature gamers: there are many disturbing themes, and the player is faced with tough decisions. A world of shadow hides unspeakable secrets, and the player will have to make choices between corrupting power and personal integrity. In some ways the story reads out like a drug addict's: after a certain point in the story, the player will constantly fight an urgent, consuming desire, and giving into it is destructive to both the player and whoever they face. This can get pretty creepy, and at times frustrating; Mask of the Betrayer is much more of an adult's game than the original campaign was [odd, considering ESRB gave it a teen rating - Ed]
The story is told mostly through interaction with Rashemen's various inhabitants, living and incorporeal. The writing is of high quality throughout, although I have to say it's somewhat wordy. To really get into the plot, you'll have to read page after page of dialogue, books, notes, and so on with a fair bit of focus. Perhaps then you get the satisfaction of guessing the various possible outcomes behind dialogue options, and make informed rather than random or alignment-dictated decisions... ...Mask of the Betrayer is a chilling, almost horror-like adventure, but there are very few opportunities for chillin' in it. Your terrible affliction haunts you most of the way, and you'll have to be at the top of your game to beat the odds stacked against you. In practice, this means a lot of effort and quite a bit of headache trying to figure out the best items, weapons and spells for your character and companions. On the other hand, an uber careful character build makes it possible to waltz through the game, soloing every combat (or so I'm told).
...Mask of the Betrayer is a great epic level fantasy role playing campaign, based on aging and limited technology, with two glaring flaws: a dysfunctional multiplayer mode and a very high barrier of entry. That said, if you finished Neverwinter Nights 2, this expansion is definitely worth getting.
