Calling it the "hardest speedrun ever" when you haven't even done a run of it (or any game, for that matter) is very questionable.
It's the hardest speedrun ever in ScorpioX2's world. That's fair to say.
I was reading your description of why you like Domina, and it sounds exactly like me when I talk about "Don't Starve" Adventure Mode- It's randomized af, and you have to know how to deal with every enemy you encounter based on what items you can create with what the world happens to give you. Completing the game is based entirely on exploring the map, so running into random enemies and traps is part of the deal and fairly common. Resources are random, based on what the map wants to give you, so you have to know the tech trees and multiple ways to get different items, etc.
Anyway, when I get time, I'm going to check out Domina, because it sounds like something I'd like- and if you're ever looking for a new challenge, keep DS in mind.