Hey welcome to the doomworld!
My recommendation for a wad that has a medieval style would be eternal doom.
Just as a warning, it has a lot of puzzles, So I don't know if you're going to like it or not.
It's more likely that he ran out of ideas or didn't have enough time to create new music, considering that the game's soundtrack was only composed by one person.
Next to the sound effects of the super shotgun, the door and the chainsaw, the sound of the revenant's slap is my favorite sound effect, because it's so funny to hear when he fights another demon.
I think epic 2 would be fine with a new the midi pack, I'm not saying that their midi selection that is already in the WAD was bad, in fact that selection is good, but imagine, several original midi in egyptian style made by the doom community.
Does this mean that this is the first time Hissy has appeared in a media other than doom?
Edit:Nvm, this is not hissy, this is just average cacodemon, Although the smile in that photo look similar to her. hissy is supposed to look like this: