The Elder Scrolls IV: Shivering Isles is the official expansion for Oblivion -- the 2006 RPG and Game of the Year. It features more than 30 hours of new gameplay as you are sent to explore an entirely new plane of Oblivion -- the realm of Sheogorath, the Daedric Prince of Madness. Shivering Isles adds to the existing world of Oblivion, so you can continue playing with your existing save game/character, or create an all new character just to explore the new content in Shivering Isles. New creatures, weapons, armor, ingredients, branching questlines, and more await in the land of Mania and Dementia.

Enter the world of the Madgod -- the Realm of Sheogorath.  Inside this torn plane reside the sublimely creative and the completely psychotic. Something is happening to the Shivering Isles and Sheogorath himself looks to you to be his champion and defend his realm and its inhabitants from destruction. Do you have the strength to survive his trials, to tame a realm fraught with paranoia and despair, and wear the mantle of a God?

Source - www.bethsoft.com (publisher)