Songs of North (link might be broken) is a location based game described by Franz Mayra (int the Receiver) as:

a mobile, location-aware multiplayer game with a theme and game world resonating with elements of Nordic myths and shamanism. The restrictions of the mobile device as a gaming interface are here translated into design solutions that actually turn such shortcomings to advantage. For example, the mobile game deck is conceptualised as a shamanic drum that operates as a window into the 'other reality' – that of the spirit realm where normally invisible friends or foes can be perceived and communicated with. Rather than focusing the player on the small screen, which really cannot compete with the experience that contemporary PCs and big-screen televisions are offering, the game immerses players into a rich audio world where wolves howl and eagles screech. The mobile device can even stay in the pocket of a player who journeys through the streets as an urban shaman, simultaneously inhabiting not only the city of brick and stone but also a fictional overlay of a Nordic spiritual realm via the cues of a hands-free headset, which continuously whispers sound information into her ear.

This idea seems nice! It's developed by Tampere's University Game Research Lab.