The Shivering Isles Add-on for The Elder Scrolls IV: Oblivion has 10 achievements worth 250 gamerscore.
Reached Duke of Mania Rank in the Court of Madness
Stopped the Greymarch
Reached Defender of the Realm Rank in the Court of Madness
Reached Regent Rank in the Court of Madness
Reached Duke of Dementia Rank in the Court of Madness
Reached Honored Madman Rank in the Court of Madness
Reached Madman Rank in the Court of Madness
Reached Citizen Rank in the Court of Madness
Reached Aspirant Rank in the Court of Madness
Entered the Shivering Isles