I figured out how to make custom maps, and are familiar with how to create 3d assets from earlier, as well as textures and art. Problem is that I don't really want to do that, since there are so many good things being created anyway. I can program somewhat, but really wouldnt consider myself a coder. Lets put it like this - I am familiar with the concept of coding and can read code for the most part.

Now I am interested in trying to make mods that actually change the gameplay, but I have no idea where to start!
So lets say I wanted to change some aspect of the game. Lets say, the speed you go from prone to kneeling or something like that. Is there a guide somewhere that tackles this?

I would really appreciate some pointers on where to start reading.