Game DB News: New: Location Based Games, fact or fiction?( Game DB News )
An interesting development recently that has been on the news in several cities is a new type of game playing called “Location Based Games”. These are apparently games played out in the real world, like cities or streets or even across suburbs and even in unpopulated nature areas like hiking trails, which use different types of mobile technology like GPS receivers and cellphones to create games with many people that have to do some physical activity to play the game. And there are new companies and services that also seem to add a king of real world game to things our phones and computers can already do. Foursquare (named after the game foursquare) and Gowalla use mobile phones and awards to create a game out of places you visit: read more on the New York Times.
There are a whole bunch of other location based games being created, the most interesting example that seems to get kids excited about the possibilities is one called Pacmanhattan: a kind of real world game of pacman, turning it into a tag or catch and chase type game (note: this does not look very safe to play in a city.)
There are also a full list of other types of locative games on the wikipedia location based game page you can read about: Wikipedia.