Ingress

For the past year, the Ingress beta has been as much an exclusive club as it is an augmented reality game -- you've had to request an invitation to play. Google and Niantic Labs must want more of us to join the party, though, as they've quietly dropped the invitation requirement. Any Android user interested in virtual turf wars now just has to download the beta from Google Play to start claiming territory. The promised iOS version still isn't available, although Niantic Labs' Brandon Badger recently told AllThingsD that the port should be available sometime in 2014. While that's a long time to wait, iOS players will at least have plenty of opponents once they arrive.