Board Thread:Troubleshooting/@comment-36155741-20181109095125/@comment-35798326-20181109142732

You can backup it easily, if you go to the iPad storage in the general settings.

Then choose the app an click on "Offload unused App" and you can restore the data if you lost/change your device:

https://support.apple.com/de-ch/HT201656

The Gamecenter is almost useless - it helps only with MP Games i think.