This mod that lets you fight your Morrowind character in Oblivion is one of the coolest I've seen in ages
From the creator who let you order real-life Domino's pizza in Oblivion.
Lord knows there are a lot of Elder Scrolls modders out there, but I think Nickies might be my favourite. The modder, who once gifted us the creation that lets you order a real-life Domino's pizza from inside The Elder Scrolls 4: Oblivion, put a new mod out last month, and it's as creative as ever. Cross-Game Invader Add-On for Oblivion and Morrowind lets you transfer your Morrowind character to Oblivion and vice versa, giving you an opportunity to finally confront your true enemy, yourself, in one-on-one combat.
You don't have to fight, of course. If you prefer, you can use your character from one game as a follower in the other, or even just play as your character from one game in the mean streets of the other. To make the transition more seamless, the mod also lets you import spells and enchantments that are specific to their respective game.
Given that Oblivion pared down Morrowind's broken and beautiful magic-creation system (though not as much as Skyrim did), that sounds like a great opportunity to smuggle some profoundly overpowered magic into the game.
On top of these game-swapping shenanigans, Nickies has added a new boss fight to the games, the "Tonal Invader". When you beat him in Morrowind, he'll escape into Oblivion, so you'll have to find him in that game to finish the fight. Nickies says that "Variables like if you disarmed him in Morrowind are carried over, making the boss fight one coherent experience!"
Nickies has implemented a "pretty basic story/lore framework" to justify the Tonal Invader's presence, and has packed the boss' segments "with depth and easter eggs" for players to find. The modder encourages "exploration and tinkering in the relevant areas" to uncover them all as you embark on your game-hopping, time-defying adventure.
Installing the mod in either game is a little more complex than the process of dropping an .esp in the Data Files folder that you'd normally use to mod an Elder Scrolls game. But Nickies includes detailed instructions on the mods' pages on the Nexus website, and they don't really need you to do anything more complicated than open Notepad a couple of times.
If that sounds good to you, then you can find both the Oblivion and Morrowind versions of Cross-Game Invader Add-On over at Nexus Mods.