A Google project hinted at in a number of cryptic messages around the Internet has been revealed as a massively multiplayer online game that uses the real world as its map. Players can attack and defend virtual control points at landmarks — but the catch is they have to actually be there.
Other apps and games have used physical presence as a gameplay element, but "Ingress" is likely to be the largest-scale use yet.
The idea is that scientists have accidentally released a mysterious energy into the world, which is coalescing in locations known as portals — and portals are only visible to those playing the game. Any nearby monument, building or other landmark could be a portal, and they'll be under the control of one of the game's two factions.
Using your phone (Android only at first, iOS version to come) as both a GPS device and game controller, you'll be able to hack portals or protect them, and doubtless take other actions that have not been revealed yet. Controlling multiple portals grants your faction territory, and there's a larger strategic metagame that's visible through a browser client, but not from players "on the ground."
"Ingress" is in closed beta now, but you can sign up for an invite at the official website.
Devin Coldewey is a contributing writer for NBC News Digital. His personal website is coldewey.cc.