@brook I love all those ideas! I think I've heard of people doing some pieces of that before, like a solar-powered file server that was only accessible if you were next to it that may or may not have been connected to geocaching?

Speaking of GPS, that seems like a totally viable way to try it out. Looks like some artists in Minneapolis attempted it in 2014, but I can't find evidence that they completed it. http://www.citypages.com/music/leav-a-gps-based-app-for-twin-cities-music-and-art-explorers-6636537