This looks awesome! I just got it, but haven't been able to play using iPad1 (iOS 5.1). Fair enough, the description does say it may not run correctly on older devices, but perhaps you could be a bit more specific.
I got as far as the "now let's learn to move" part of the tutorial, which incidentally took about ten minutes because the intro (about 'there is evil' etc) seems ungodly slow, perhaps you are using some fill-rate dependent methods that this ancient gpu can't handle. Looking at the device log it appears to be killed by the OS due to simply using too much memory (iPad1 only has 256mb total).
Unfortunately now I cannot seem to get even that far, as the app exits when I choose 'New', like the other guy says above. I thought this might be caused by reading some save file, because it didn't happen the first time, so I reinstalled the app but strangely it had no effect.
I was encouraged by the mention of "support for older iPads" in the app description, but if I had to guess, I would say you have not actually tried it on a real device? In further support of this theory is that the app does not even start at all on my iPod4 running iOS 4.3, even though it should according to the app store description, and the crashlog says you are using an [URL="http://stackoverflow.com/questions/8342411/getting-dyld-symbol-not-found-objc-class-nsjsonserialization-on-ios4"]API that does not exist in iOS4[/URL].
Even though in theory a lot can be done with the simulator, perhaps it would be better to make the app description/rating only include real hardware you have actually checked with. I know not everybody has as many old junk devices lying around as I do (and Apple only makes life harder because downgrading iOS is so damn difficult), but iirc the app description can be changed anytime, so you could update it whenever you come across a real device to check with.