Serious Sidhe
Egyptian themed mini-episode for Heretic (4 levels):
Download: https://www.doomworld.com/forum/topic/97586-serious-sidhethe-full-encounter-10-version/
Gameplay: https://www.youtube.com/watch?v=ArCSisBYkjk

REKKR
Viking-themed mod for Doom, but since there's a standalone version (no Doom or Heretic required) I think it fits here.
The standalone version includes Chocolate Doom and it's ready to play.

Download (v1.16): http://manbitesshark.com/
Cacowarded in 2018: https://www.doomworld.com/cacowards/2018/best2/
Gameplay: https://www.youtube.com/watch?v=_RWcYBeeYfg&t=6s

(Deleted)

It's resolved.

Forgive me any such have been listed before--I didn't see any when looking through the forum and thread--but are there any good mods--in particular custom campaigns--for Hexen II?

I just finished playing the base game, and thoroughly enjoyed it. Portal of Praevus is, of course, not available. Thus I'm somewhat hungering for something else to try--fan-missions!

(And bonus points if they add new weapons or enemies!)