What areas of mathematics are affected when writing an MMO game engine?

Question

Mathematics

Since it is impossible to study everything and everything, I would like to know what areas , minimal but basic, without which in any way, will be 100% involved in the development of 3D MMORTS / 3D MMORPG ?
While the questions may seem broad, they are not.
Anyone who has been involved and tried himself in a full-stack in game dev , like me in web dev, should roughly understand what areas and where are applied, physics, mechanics, rendering, modeling, and so on.
My goal is to make a list and go through it and study it. When I studied sorting algorithms, I really never used it for the entire time of development, there are already libraries, packages that do everything by writing simple methods. I'm sure in game dev the same situation, but still, memory control is more critical there than in the web.
The info is pretty scattered, maybe somewhere there is something like this

Answer 1

It's a good question in its own way.
Sorting algorithms are a traditional material for mastering the topic "algorithmic complexity", for the sake of it you studied them, although you did not understand this)
The idea of ​​​​writing an engine with this approach looks somewhat utopian. What engines do you know about? Have you seen implemented games (at least one) in all of you known? What engines did not suit you? Well, yes, the owner is a gentleman.

• Combinatorics (at least have a concept of a combinatorial explosion)
  
• Basic knowledge about graphs
  
• Elementary geometry / stereometry - where without it in 3D