I can second these. I want to know how I can make my own mod for KK because it's the only game I've played in this category that has the potential for a good game part and not just entirely be focused on the lewdness.
https://wiki.koboldkare.com/index.php/Modding their wiki on morning is bare bones but has good bones. Basically it seems like knowledge of unity is what you are gonna need the most