The fitness app, which has been created with the NHS and funded by the Department of Health, aims to help people walk 10,000 steps every day by pretending they are on the run from terrorists.
The game, called The Walk, challenges its users to deliver a package from Inverness, the scene of the fictional assault, to another destination in the UK after a bomb explodes at the Scottish station.
Those using the app must walk in the real world to survive in the game and also "save the world".
The game has 65 episodes containing intricate, fully-illustrated maps, 800 minutes of audio story and hundreds of collectible items to explore the world of the story.
Health officials have said the app could help in the fight against obesity.
Its maker, Naomi Alderman, said: "The Walk is designed to be addictive, in the best possible way."