Zombies, Run! is the first ever fitness game with a story and is becoming a huge hit with joggers from Italy to Australia.
The game, downloaded as an app and played on iPhone or iPod, puts the player in the centre of a zombie apocalypse.
It has become so popular it has reached 14th place on the list of top grossing apps worldwide and is the third most popular top grossing health and fitness app.
Sales are expected to hit the 100,000 mark soon.