CountChocula
Keeper of the Watch
That's one thing that really has me puzzled. If you blot out the sun then…
… plants and vegetation die off…
… animals have nothing to eat and die off…
… people have nothing to eat and die off…
… vampires have no blood to drink and… I guess, they die off?
Meh. I'm reading too much into this. It's a videogame. Maybe blotting out the sun can just be 'fun' and doesn't have to be realistic.
The "sun" in this case not actually a celestial body comprised of helium and hydrogen, but simply a hole in the veil of Oblivion which allows the light of Aetherius to shine through. (Aetherius is the plane which is the origin of all magic and arcane arts.)
I'm not sure how photosynthesis works in the Elder Scrolls game world, but it's probably very different from our world.