Because there is a mod, that I use and the creator is not more in the game, and he has abandoned the mod. Since the update I cannot use the mod, and I would like to know if it is possible to convert the mod from the zip file I have to the new engine.
It’s impossible if you don’t have source files. Some authors sometimes pass their source files to other modders so the only way is to find this author in Steam and ask him/her to give you sources.