If you're having some technical problems, try some of these steps:

Check the Known Issues articles. It's quite possible that we've already spotted the problem and are doing our best to fix it.
Restart your device.
Check for available game updates in the App Store.
Check for available software updates for your device.
Make sure your device meets the minimum system requirements for proper gaming—at least 1 GB of free memory.
Delete the game and reinstall it. Don't worry: If your in-game profile is linked to your iCloud account, you won't lose your progress!