It is very real.
About 3 years ago a game called Ingress was launched. It was one of the first mobile games that took the environment around you as the gaming world and required the player to actually move about in order to play it.
It is thus an augmented reality GPS based game. The success of the game and the technology showed what the future of augmented reality games could be all about. The entire planet could become the playing field and the gaming app, via a cloud, could place objects on a type of Google map, forcing the player to physically go to these locations to find the objects.
Then, in 2014 Google launched an April Fool's Day joke about a possible game to catch Pokemons IRL using a phone app. In the end it was only Pokemons hiding on a regular Google map, but the joke did spark ideas.
Little did the world know that meanwhile Nintendo had approached Niantic Lab, the company behind Ingress, to develop an Ingress-like game, but with Pokemons instead.
Mid-2015 the launch was announced via a trailer: Pokemon Go.
Pokemon Go will give the player the ability to search out Pokemons, catch them via the app or an external bluetooth-driven, wrist-worn pokeball, train them, exchange them and launch them into battles with other players. The Pokemons will only be visible within the Pokemon Go app, but eventually there is the option of making them visible via augmented reality glasses, such as Google Glass.
The game will launch in 2016 for iOS and Android and will no doubt revolutionize mobile app games and mobile gaming in general as it will force people to leave their house to play the game.