I personally think this is great. What better way to get those South Park-esque World of Warcraft fatties out of the chair and into the real world. Running to progress the story line is a fab idea, and gives a definite incentive to keep going - if the copy is good that is. 

It will be interesting to see what adver-game products eventually pop-up in it too. Does neosporin work on Zombie bites?