Nah, it's actually quite easy, it's just that sub-1hour took a LONG time to get to. You're not really using many statboosters until Arrogance, unlike Deity%, where you may have to pop a Hot Bean Juice or Guga at some problem chapters. On Mortal% you don't really get any big runending bs thrown at you (unless you get garbage RNG) until basically the final chapter (with the exception of like, Koeli-Sumash, but that's already an annoying chapter) whereas Deity%, and even Hero%, bad RNG is a lot more likely

maaaan gettin this was so painful lol

cause the night before I threw 2 runs at the last chapter XD Probably a rare moment where the damage reduction aspects are legitimately practical Could've had a better Koeli-Sumash and maybe a better Edge of Ascension but other than that I do not think I'm comin back to Mortal% unless another gamebreaking skip is found (Like the Darkest Hour skip), some type of category extension, or someone straight up beats this lol.

Is it possible for more categories aside from Vanilla Full game? Individual levels, Reverse Recruitment, Anything goes (Campaign customization) etc.

Pretty late on this, but the game is currently on patch 1.55. From what I can remember off the top of my head, the game is kinda harder but there's a few chapters that did get changed. On chapter 16 (on Deity mode at least) while it's lowish, there is a small chance that Fenton and Faust can die so you can miss on their promotion. Chapter 19 got some changes so it's a few houses and stuff instead of just a box, but it still plays the same (escaping is somewhat easier however). Chapter 25 is notably shorter, as you don't have to go through the beginning area of super jacked enemies plus the long hallway. Idk if this was a thing in past versions, but Varic actually attacks on enemy phase if you're at 2-range so if you can't tank a crit might wanna keep that in mind. Not sure but the ship in chapter 12 might be able to get destroyed quicker, though it may be a Deity mode specific thing. Also for classes I'm pretty sure the Acolyte/Conjuror healing was nerfed, and I think Champion was buffed. Also Elias got buffed so he tanks better in the early game.