The Elder Scrolls IV: Shivering Isles Q&A, Part One

RPG Vault is offering up the first installment of a new The Elder Scrolls IV: Shivering Isles Q&A with Bethesda Softworks design director Bruce Nesmith.
Q: Approximately how much playing time can the average player expect, and to what degree will it be replayable?

A: There are easily 30 to 40 hours of gameplay in the Shivering Isles. We knew that if the original game had 200-plus hours, we would have to make our expansion as big a most other games just make it feel right.

The replayability factor is somewhat higher. The dungeons respawn using the same rules. Many of the quests have multiple branches. The main quest has a couple of major decision points that affect future quests. For example, at one point, Sheogorath will offer to make you Duke of Mania or Duke of Dementia. Which you choose affects a number of future quests.