We have two main methods for saving your progress which also mean that you can sync your game across more than one device.
If you are playing on an Android device, you can use Facebook to sync and save your progress.
If you are playing on an Apple device then you can use Apple's sign in.
If you wish to play across both Apple AND Android then you'll need to use the Facebook option.
To access both of these options, just tap on the settings icon in the game; it will take you here where tapping on 'Save progress' will show you the options:
We do have a cloud save available which will keep your progress as long as you don't reset or lose your phone.
If it is not possible for you to use Facebook or the Apple ID and you are concerned about progress loss then keeping a note (or a screenshot!) of your Game ID (also seen in the screenshot above - it's below the version number) will aid us to restore your progress if lost.