Looking to start a bare bones mod

So I am looking to start building a completely custom game mod (ie. not use the core maps, quests, etc.) but just trying to find out the best way to get started. I basically want a starting point of a mod that includes all the core game assets (art assets, core scripts, etc.) but not include most of the things that are core to the grim dawn “world” (mainly the maps / quests / masteries). What would be the best way to get start on something like this?

Take all assets except for maps, quests, conversations and tags and don’t take the database.