I think it would be cool if we have a strategy/RPG 2D sidescrolling game in which we roleplay as a runner... who could choose to run anything from a 200m dash to an ultramarathon. It'd have its own full-fledged statistics system, equipment system, training system, career mode, what have yous... Anything that could come from a hardcore strategy/RPG game.

Oh, and make it border on fantasy/science fiction the further you get into the game. Maybe as time passed, more technologically advanced equipment and apparel would be available? Or maybe all the marathons you joined are part of a much larger scheme, in which a sorcerer is looking for the best runner in the world so that he could leech his soul out of his body. :D

I can't help it. Running half-marathons is a huge part of my life :) Might try marathons soon.