Modification (Oblivion)

A modification, also known as mod or plug-in, is a software file that changes some aspect of the Oblivion game. A few exist for the XBox 360, but they are most overwhelmingly common for the PC platform.

Mods do not come pre-packed with the retail game. They are created by the game's fans, usually using the Elder Scrolls Construction Set for Oblivion. They can be downloaded from the internet, usually for free. Bethesda also offers official studio-built mods, which may be downloaded for a small payment.

Most mods are in the .esp format, and must be enabled as a Data File when the games first loads (see the 'Data Files' dialogue on the PC, as the game loads). Some mods may take the form of textures that replace those in the game, or .xml files that adjust display characteristics. Textures and .xml files do not need to be enabled as Data Files at start-up.

Fan mods range from cheats, new content (items, areas, buildings, quests, spells, NPCs), fixes, gameplay variations, and graphical changes (textures, user interface). For example, some make the game more realistic or add significant new gameplay or even whole new lands and major quests. Others improve the game's appearance by using higher resolution textures.

Official plug-ins
These are official plug-ins created by Bethesda that have been released and are for sale at OblivionDownloads.com, or from Xbox Live Marketplace on the Xbox 360 (in order of release date):
 * Horse Armor (DLC1)
 * Orrery (DLC2)
 * Wizard's Tower (DLC3)
 * The Thieves Den (DLC7)
 * Mehrunes' Razor (DLC9)
 * The Vile Lair (DLC5)
 * Spell Tomes (DLC4)
 * Knights of the Nine (DLC8)

PC users can also buy The Elder Scrolls IV: Knights of the Nine retail pack for an MSRP of USD$19.99, or GBP£19.99, which contains all of those plug-ins.

For PlayStation 3 users, the Knights of the Nine plug-in will automatically be included with the PS3 version of Oblivion. It is not known whether the other plug-ins will be made available for download for that console.

Unofficial mods
Some popular mods in alphabetical order:
 * Aundae In Cyrodiil – Improves the vampirism experience
 * Beyond Cyrodiil – A network of mods working to mod various areas of Tamriel
 * BTmod v2.20 – Interface mod allows for larger map, removal of quest and location markers, and smaller text to fit more items on-screen
 * Modular Oblivion Enhanced – A comprehensive mod that enables various features that were not meant to be in Oblivion, such as playable male & female Dremora with dialogue, increasing realism and freedom, as well as adding many other features including a Vampire Clan and Night Mother rituals. The newest version also adds the ability to become a Lich or a Werewolf and adds scythes as weapons.
 * Obscuro's Oblivion Overhaul – Major mod that makes many gameplay rebalances and tweaks; adds creatures, items, NPCs; adds some textures; and is bundled with other various mods
 * Scorn's Vampirism - Enhanced Vampirism, you become more powerful with each feeding.
 * Silgrad Tower - Building the mystical city, and rebuilding part of the Morrowind province, with new models, tilesets, and more.
 * wz Inventory – Inventory changes make it more like Morrowind's, smaller text, larger map

Rumored plug-in
Dragonfire Castle was a long-rumored plug-in, which had surfaced around August 2006 with the only information coming from a supposed image scan (see article). It is unknown whether Bethesda is actually working on this for a future release, or if they've ever worked on this previously. No other information has been released since then.