How deep can you get?
Tap to swim up. Stop tapping and you sink. That is the whole of it — everything else down there is just the Trench.
Open Customise from the menu and tap Restore Purchase on the unlock screen. Make sure you are signed in to the same Apple Account you bought it with. The unlock is a one-time purchase tied to that account — reinstalling the game, or installing it on another device you own, restores it at no cost.
If the restore says no purchase was found and you are certain you paid, email us with the date of purchase and we will look into it.
There is a speaker button in the top right corner of the play screen. Check that, then check your device's silent switch and volume.
Leaderboards need Game Center. Check Settings → Game Center on your device and make sure you are signed in. Only your best depth in a mode is submitted, and only when you beat it. Declining Game Center costs you the boards and nothing else — the game plays exactly the same.
Yes, entirely. There is no server. Only the leaderboards and the purchase need a connection.