World of Fourcraft, real-life Risk
World of Fourcraft is a FourSquare hack that turns New York city into a giant game of Risk. Its was done during Game Hack Day NYC that was held June 25th and 26th. Quote from the Mashable article: "World of Fourcraft uses Foursquare and Google Maps APIs to turn New York City into a giant game of Risk. Users decide which team they are on by swearing allegiance to one of New York City’s five boroughs. Checking into a neighborhood on Foursquare is the online game’s equivalent to placing plastic man on a country in the board game. An algorithm decides who owns each neighborhood using the number of people who have checked into it on each team.".