Vlinder is an app that makes your device part of a network through which a single vlinder (Dutch for butterfly) can fly. The Vlinder is only at one device at a time. When Vlinder flies to your device you'll receive a notification and you can see it in your surrounding. It will then fly to the next closest connected device, ad infinitum.
The app is available for free and you can download it from the Play Store here .
A selection of screenshots of Vlinder around the world:
11th Athens Digital Arts Festival, Athens, Greece