I didn't realize that the Kindle Fire was the only Android-based device you had, and iOS apps are not compatible with Android devices, such as the Kindle Fire. Unfortunately, Google doesn't allow the Fire to be registered with them, so (as you have discovered) you aren't able to purchase apps from Google Play. It's unfortunate that the Fire is excluded from making app purchases from Google. I can't speculate as to when we might have our games available on the Amazon Appstore, but we do intend to make that happen at some point.