Open the game → gear icon (Settings) → scroll to Support & Contact → Restore Purchases. The unlock is tied to your Apple ID, not the device.
Progress syncs through your own private iCloud. Make sure both devices are signed into the same Apple ID with iCloud enabled, launch the game once on each, and the further run wins. Progress never moves backwards.
Leaderboards and medals need Game Center switched on in your device settings and a connection to submit. Everything else, including the whole campaign, plays offline; scores earned offline are submitted the next time you are online.
The first 8 missions of the main campaign and the first 3 missions of each Elite campaign are free, with every battle mechanic included. One purchase unlocks everything else, forever. No ads, no subscriptions.
Purchases are processed by Apple, so refunds go through them: reportaproblem.apple.com. Apple usually answers within a day or two.
Check the Music and Sound Effects switches in Settings, and the hardware mute switch on your device. If something still sounds wrong, write to us. A description plus your device model is enough.
It has been filed, stamped, reviewed and respectfully ignored. The tanks are training harder as we speak. Thank you. Seriously.
Ideas, bugs, kind words: a real person reads every message.