Going for a run is a great way to get exercise and feel rejuvenated, but it can also get repetitive and boring. By contrast, digital games can be very engaging and addictive but traditionally force players to be physically inactive. This project is a mobile phone application that transforms a run into an immersive game by presenting a series of story-based running tasks to motivate the player. Requiring that the game be played while running constrains the design in terms of both input and output, and this system demonstrates ways to manage those constraints while still providing a compelling experience. A six person evaluation validates the concept and offers useful design feedback.