I certainly hope you do not need to give away the whole game in order for someone to make a mod. But as of yet I am unfamiliar with any ‘hooks’ you can put in your game (if they exist) that would allow it to see a ‘mod’ in a folder and either replace stock content or add new content. Oh, and by ‘give away the whole game’ what I really meant is more along the lines of how much ‘source’ from the game would need to be open to people…