Wherigo is a game with an interisting concept. Is an adventure game but in the real world. Confused?
There are two sides. You can build the game or you can play it. I think the citation below ( taken from http://www.wherigo.com/about.aspx) explains the concept in simple terms:
Building
Using the Wherigo Builder application, Wherigo authors can build interactive adventure games, tour guides and other innovative activities for Wherigo players to enjoy outdoors. The Wherigo experience combines physical and virtual elements, overlaying engaging story lines and useful information onto a real-world background.
The basic building blocks of Wherigo are zones. Zones are areas on a map that represent locations in the real world. Zones can be created to be any shape an author chooses and are usually dependent on the type of experience the author desires to make and share. For instance, if an author wants to develop a tour, a zone could be created around a specific landmark.
Once the author is finished creating the experience, it is uploaded to the Wherigo site as a self-contained Wherigo file, called a cartridge. The published file is made available at www.wherigo.com to be downloaded by players equipped with the Wherigo Player application.
Playing
Using the Wherigo Player application and a GPS-enabled device, participants can visit physical locations, take and use virtual items, interact with virtual characters and solve real-world puzzles.
As a player enters and exits a zone using a GPS-enabled device, the players experience what the author intended for them, including viewing media, receiving directions or tasks and hearing sounds on the device. For instance, when a player walks into a zone, a player could “talk” to a virtual character, “pull” a virtual switch or “give” a virtual item to a character. As the player continues to move from zone to zone, an author’s fictional story, tour or adventure game can be experienced using Wherigo.
Wherigo can be more then just a game. The concept also aplies for a lot of other things, like tour guides for example.