Two questions: Is the savefile for this mod seperate from the original game? Like, if I complete a level in this mod, will it transfer over to the original game, and vice versa? If it IS seperate, how did you do it?
you can use Undertale Mod Tool to decompile it. there’s also the source code at https://github.com/apia46/IWannaLockpick but you need GameMaker Studio 1.4 to use it