World of Fourcraft
There's a war on in New York City. The lines of loyalty were drawn way back in 1898 and, ever since, it's been battle for borough superiority. A team of hackers has ushered this county rivalry into the internet age, turning the Big Apple into a giant Risk board where check-ins replace dice rolls and armies are gathered on Foursquare. In World of Fourcraft users pledge fealty to a particular locale then, for the honor of their homeland, check-in to wrest control of neighborhoods from their residents and defend their own turf from potential usurpers. The whole project was whipped up last weekend during a hackathon at New York's General Assembly. At the moment it does little more than tally check-ins, but the creators plan to add new features in the future. Now, go forth and do battle for your block but, don't stray too far -- to the north and east of the Boogie Down Bronx, and the south and west of the Slums of Shaolin, lies The Waste Land.

The Engadget app for Windows Phone is here