Attached images show rough UX to follow,
Two different styles to choose from:
 Flat - see: QuizUp, Nike+ Running, Strava
 3D Game - xbox> kinect training, ea active, zumba fitness, <mobile> max axe, Dr Newton
User comes onto app and sees a home screen. This is where they can purchase upgrades with their hard earned coins, where they can see what's been going on recently, their incoming challenges and friend's recent activity.
Then there is the challenge screen, where you select a friend to send one of your runs to, the user's profile screen and the in-run screen showing the map, progress and stats. Most of the feedback is audio but the screen still needs to look slick.