REXplorer is a pervasive game designed to enhance the tourist experience in the medieval city of Regensburg. More about it here: REXplorer: A Pervasive Spell-Casting Game for Tourists as Social Software by Rafael Ballagas, Steffen P. Walz and Jan Borchers.

Participants will begin by renting their “magic wand” (actually a smartphone loaded with custom software and data necessary for the game) from the visitor center. (...) As they move throughout the city, players can attempt to cast spells at historic buildings using the Sweep technique that performs motion estimation by the way of the phone camera, and gesture recognition in (x, y, theta) dimensions. In response, players hear voices from magical spirits trapped inside the buildings through their magic wand (the loudspeaker on the smartphone). If they cast the spell incorrectly, the spirits will be disgruntled and uncooperative. (...) Participants may also need to duel against other participants in a spell-casting battle to achieve their goals. In addition, and more importantly, players can “cellcast” cooperatively to solve challenges. (...) As visitors are capturing media of the city in the game, the Regensburg application servers are automatically cataloging the media content they create to generate a website to show where they've gone and what they've done. During the game, this blog can be used to monitor the current game status by getting an overview of the teams' progress.

Why do I blog this? I like the interface trick using the phone camera, that's a good hack to create an innovative gameplay. The game seems also to be a good situation to have cooperative/competitive behavior.