Yeah, its a hard topic. On a side note, I am happy to hear of someone writing in C# as I am learning it now. It seems a lot tougher than C++, but I have not given up on it yet. To attempt an answer to your question; if you organize your files, the player could figure that out. It won't be easy, but modding never is. In the case of modding a map, the player would have to recreate it alltogether I think, assuming you did not make your original files easily opened in things like GIMP. being that you are writing in C# you might have to make a mod tool for the player/modder. Another thought is that you might copyright all your OC? That way any theft that drew money could be prosecuted, and you could safely allow the player direct access to all your resources.