mods in general

Hello, everyone! I'm a new user here and I want to know how SBR2 modding works. What engine was the fangame made in and how do people make mods? Any modders here who could teach me? Does the process apply to all games and engines? I'll love to know! I want to learn to be inspired!

So, as the title implies, today I'm asking you guys about mods you'd recommend! Like my last thread, I want to find some pretty OP mods (at least to see. You can add a link, a video, or just a image or gif.)