Remember the game "Track and Field" from Konami?
http://www.youtube.com/watch?v=RLeNExXflkc
That game was pretty cool.
A running game would work pretty well as an app...not too much expectation and good enough to pass the time.
I was thinking an Ultra Marathon or a Trail Runner game would work pretty well.
It's simple: The runner would have to avoid hazards (bears, cliffs, hobby joggers) and hit certain check points and water stops at specific times in order to finish the race. You'd gain "power ups" when you obtain energy bars and would have the ability to the surge and outkick for a few meters/miles.
Bonus points for what place you finish in.
Finish the race and move to the next scenic course.
I'd download that.