No support from Aksys, incompatible with certain devices
Only restriction listed is the minimum iOS version; can be purchased on iPod Touch 3rd Gen (and presumably iPhone 3GS), but cant be played due to a lack of non-Retina display mode. Most of the game is cut off the screen despite apparently running fine otherwise. Contacted Aksys support nearly two months ago with no response; the patch neither acknowledges or fixes the issue, and the game can still be purchased and downloaded on these incompatible devices.
Personally I loved the original 999, but I cant approve of an apparent cash-grab with no support behind it.
JimBobVII about
999: The Novel