Celestial mechanics

I got myself interested in that weird polar orbit (NRHO) around the Moon again, have been sent to a very explanatory video from creators of an orbit plotting program -

Then I've been shown a paper by NASA, explaining their interest in it - https://ntrs.nasa.gov/citations/20150019648 .

Here is a great picture by Richard Penn from
https://commons.wikimedia.org/wiki/File:Delta_V_Earth_Moon_Mars.png

and I would like to take a closer look at a simulator called "Children of a Dead Earth" if I have enough time.
https://store.steampowered.com/app/476530/Children_of_a_Dead_Earth/