Characters begin at level eight. Players can choose all classes available in NWN 2 and Miranda indicated that MoW is a boon for players who like 'weaker' characters. All character classes -can- be successful in MoW.

Starting equipment tailored to a level eight character is provided after the introductory sequence. Additionally, players will be happy to know that characters from NWN 2 or Mask of the Betrayer can be brought into Westgate. But while a level thirty multi-class, uber-equipped character can be brought into MoW, according to Russ Davis, there won't be much of a challenge or fun to be had.

The story arc begins with characters finding a 'Domino mask' in their equipment with no real knowledge of how it got there or why it can't be thrown out. All that is known about the mask is that it has to do with the shadiest of the shady Night Masks. Thieves, cutthroats and social miscreants, they wield nearly unprecedented power in Westgate, hence the player's journey to this anti-tourist spot.

While MoW coincidentally focuses around a mask as did NWN2's first expansion pack (NX1) Mask of the Betrayer (MotB), Ossian had pitched their idea long before NX1 was released and Ossian made the right decision not to alter their plans because of MotB. Speaking of which, you won't need the MotB expansion to play Mysteries of Westgate but if you do have it, then you'll be able to take advantage of all the class features in the expansion.

In your quest to find out how to learn more on getting rid of the mask, you travel to the City of Westgate where the adventure begins. There you find out that the mask is linked to a powerful criminal organization called the "Night Masks", and you have to choose sides in a war of factions who are trying to control Westgate. Because Atari told Ossian to really focus on the story instead of new content, the module has many branches in a non linear path with 16 side quests. While almost all of the adventures take place in the city and under the city, there are also some ship battles. The city is divided in four main areas; The harborloop, where you arrive, the market triangle, the arena district and the undergate, below the city. To help make travelling around the city easier there are several transition points that take you to the overland map where you can just click to travel immediately to that location without having to run through the city.