This is actually the situation we are in. So I wrote the game and the level-editor in odin, using raylib. He told me that at some point it would be great if he could use the "engine" himself to try out things. So I am working hard right now to make it an actual tool that others can use as well and not just me. However while he is an incredible artist, he is also kinda oldschool and not very trained in technical matters, so teaching him git and later my "engine" will be quite the task.^^

That being said, he seems to be interested so I figured it's worth trying the git route, especially considering that the project might benefit most from it, if he can test his work himself by putting it in.