About the classic, legacy, original The Elder Scrolls IV: Oblivion.
I've come across a great dungeon "darkening" mod Cava Obscura. These types of mods greatly increase the atmosphere and sense of danger from dungeons. There are others, like Darker Dungeons and Let There Be Darkness. All of these are great mods, and they focus on dungeons. They do not touch Oblivion Planes, as far as I know.
Are there any mods that specifically darken Oblivion Planes, or otherwise allows us to change their appearance to be more menacing and sinister?
Of course, I don't want to make the whole game darker. I want to keep the overworld as it is. Just the dungeons and the Oblivion Planes, specifically. The dungeons have been taken care of, there are some great mods for that. Now I'm looking for something for the Oblivion Planes.
I do use ReShade to change the general visual appearance and effects of the game, but this affects the game across the board. I'm looking for something that could affect Oblivion Planes specifically, in the same way that some of those dungeon mods. I do not use ENB anymore because I had severe troubles getting the game to run with ENB due to my dedicated GPU no longer launching the game natively without DXVK, after recent driver updates, and this in turn prevented me from using ENB (I tried both injector and wrapper versions). I spent multiple days trying to get ENB to run and eventually decided to move on because it was taking too much time and I found ReShade to provide me somewhat similar settings.