Parallel Kingdom was a mobile location-based massively multiplayer game that placed a player in a virtual world on top of the real world, based on the player's GPS location. Parallel Kingdom was the first location-based RPG for the iOS and Android platforms. The game was developed by PerBlue, a privately held mobile and social gaming software company founded in 2008 and based in Madison, Wisconsin. In 2011, the game's user base surpassed 1,000,000 players worldwide. The game closed on November 1, 2016.