Turf is a free location based iOS game set in the real world. Earn coins for visiting real life locations, take’em over, build on top of’em, and collect rent. Beware your fellow geographers who want to take your sugar!
Built on top of Foursquare
Here’s the Kickstarter video that shows some gameplay (project has already been funded):
Also: this looks like the first game built on top of a check-in service that’s actually appealing.
(via The Verge)