SureAI

It seems like the dungeons and nights in Nehrim are even BRIGHTER than in default oblivion to me.
I feel like there must be something wrong, but even when I turn the gamma down to 0, I still see perfectly fine in a mine with no light sources. I also see no affect produced from torches at all. Am I experiencing some sort of glitch?

hmm, i experience unholy dark dungeons in my game. literally i can not see anything sometimes when there is no any light source...torch is useful but an infravision spell is better. i think you have some sort of glitch.

Yes, there are a few Dungeons/Corners which are pitchblack. You need a torch or nightvision or light spell to make it through them.
In general, Nehrim outdoors is the same as Oblivion, just more rainy. Indoors its generally a lot darker than Oblivion.
If your gamma is 0, you should not be able to see anything actually.
You should check your grafics driver and Monitor settings.

I don't think anything's wrong with my monitor, because in regular oblivion when I use darker dungeons / nights, everything DOES get extremely dark.
Also, in Starcraft II, I had to turn up the gamma significantly to be able to see the terrain through fog, so there's another thing where it's dark on my monitor...

I'm thinking it's some sort of glitch with the game, unless all of the early on dungeons are bright enough to see in (starting and level 1-7 area?). Anyone got recommendations for this?

Oh also, when I set the gamma on my monitor itself to 0, I can still see, it just gets a little darker.

Could someone please help me? This breaks immersion terribly

Did you Oblivion installation have any mods or replacers?

Only operation optimization. I had nothing else installed besides the 1.2 patch.

Hmm, just a thought, if there is a problem with lighting, might it cause darkness to disappear? Maybe there is no light an no darkness, just standard background light everywhere?

Hmm, what I would do:

Delete the oblivion.ini and see if the plain standard automatically generated one works better.

If not, reinstall everything - minus operation optimization.
That should give the fastest results.

Delete the oblivion ini, or the nehrim ini? Because I feel like deleting the oblivion one wouldn't do anything at this point...

oblivion.ini since it is the one the oblivion engine uses.
It may not help, but it is way quicker than reinstalling.

Deleting the ini didn't help me... Is my only option now to reinstall?

Its your best option. You wont loose your savefiles or anything, you only might have to reinstall mods as well.