In Shadows app for iPhone and iPad

InShadows is a iBeacon-enabled game of tag. It requires at least two players, who each have the InShadows app. Players are divided into “Hunters” and “Shadows”. They must try to outwit each other while running. Shadows will score points by tagging Hunters and Hunters will score points by avoiding being tagged. InShadows includes a timer for the game. It also has built-in “radar”, which tells Hunters and Shadows when they are near each other. InShadows keeps track of tags by changing color when two players are very close to each other. It also includes a web-based scoring system so that players can keep track of their scores across multiple game sessions.

"Continued use of GPS running in the background can dramatically decrease battery life."