NOTE: I updated the article text, seems there’s some confusion on what devices are actually supported. For now, I’d just assume iPhone 4S, iPad 2, and 5th generation iPod touch or newer devices are compatible. I’ll update again when Supergiant gets back to me with confirmation.
EDIT: Ok, full device compatibility list added to the post. In the App Store sidebar under ‘Requirements’ it doesn’t exclude 3rd generation devices, the iPhone 4, or the original iPad due to Apple’s limitations. So that part is out of the dev’s hands.