Sometimes in Skyrim you wander into a hole in the ground, fight some draugr, defeat a dragon priest, collect a shout, and leave via an exit that conveniently loops you back to where you came in. Sometimes you end up in a gloaming fungal underworld and only emerge hours later barely remembering what the surface looks like. If you'd like more of the latter experience, The Rot Below is probably the mod for you.
Impressively, it's the first mod by TheCrowKnight, who says it contains "A host of terrifying new enemies," as well as "Three boss battles" and "over 350 professionally voice acted lines." Most of those voice lines presumably belong to the villainous lich Malkifer and a bard named Adabelle you'll be tasked with rescuing, though the credits also include "The Undead Blacksmith".
