Citadel of Madness is a mod for The Elder Scrolls 4: Oblivion that is over a decade old (it was first uploaded to TESAll in 2013 and was significantly updated with the release of 2.0 in 2022). It adds new land on top of the Shivering Islands, hundreds of new NPCs live there, and new quest lines can be found that the mod describes as “comparable in duration to the guilds of Shirodir.”

Citadel of Madness was created by modder Lariatius and translated into English by Vorians. 38 quests, 15 of which are side quests, promise over 25 hours of play. 3,000+ lines of dialogue ( but no English voice acting), a variety of new alchemical ingredients and concoctions, new dungeons, and new enemies, including bosses.

Given its connection to the Shivering Islands, one would expect Citadel of Madness to be different; you must be at least level 18 to play the Citadel of Madness quest line.

To install this mod, you will need to download the file from Nexus Mods. It is nearly 900 MB, which is less than Skyrim's mod, but much heavier than some of Oblivion's mods. You must also have the Shivering Isles extended version The Shivering Isles expansion is also required, but since it is bundled with all digital versions of today's games, many people will already have it.