I am also interested in adding multiple layers to earth map in google earth. In my RPG, I use the actual earth as my campaign setting. I am looking to ad layers that consist of my own locations such as villages, towns, and cities as well as territorial borders. I have been using place markers and polygons that are built into google earth, but I was wondering if anyone know of some tutorial or software that is built for this kind of thing?

I also want to Darken the world map, creating a sort of inverse polygon, so that I can show where my players have been and darken where they haven't been. Any help would be great!