Materials on game reversing

Hello, I am last year bahelor in computer science. Untill now I have only written code(php, js, c#, c++, played with react, symfony, etc.). The work that the team(I suppose it is a team of devs) did on reverse engineering this game is magnificent. My question is: I have never tried reverse engineering a game, I heard that you had a copy of the early beta of the game and started from there. Can you give me any materials that I can read and try understanding how to reverse engineer a game/ crack a game. Because I have a game that is really close to my heart, but I have never done this as I said already. But willing to teach myself(I know that this is work for few people, but I want to grasp the basics and if you are so kind to give me ANY materials I will be gratefull). If someone of the devs behind this has materials and sees this, please send me something.

 

So the only thing created was the server-side software in order to run every game instance? But you cannot help me with how this was done. If I understand correctly.