Payphone Tag is territory game using Australia's 15,000 payphones
Turning Australia's dying payphone network into a territory capture game is brilliant.

Yet another GPS territory game, but the voice-command combat is a novel twist.
Mobile gamers, fans of location-based games like Pokémon GO
Pokémon GO · Ingress · Zombies, Run!
Turning Australia's dying payphone network into a territory capture game is brilliant.
Turns the viral Pong Wars sim into an actual competitive multiplayer game with powerups.
Geoguessr-for-audio, but lacks novelty—audio guessing games already exist elsewhere.
Hundreds of players on one map beats typical 10-50 player strategy games.
Voronoi diagrams shift per screen, forcing players to negotiate perspective.
Combines server registry with player services so you stop stitching five vendors together.