Your post got me thinking about an article that I read a while ago about a game for the iPhone called "The Hidden Park" http://www.thehiddenpark.com/
It might be worth a look if you wanted to get some inspiration, outside of the box, so to speak. I was just thinking of what you could design to make sure that you would not be in the same area as something like the Microsoft Surface, i.e. what can you do physically and from a design point of view with the iPad that you cannot do with the Surface…
It would be cool if you could use some of the features like GPS, so that the game could take place in a real world environment (like in Hidden Park). I am sure that there are "loads" of reasons why this would be a non-runner but it might give you some inspiration?
I suppose its something that would be more of a runner when the iPads were in widespread use and "some people" would not feel the urge to rob your iPad if you were using it outdoors :lol: