If your game freezes, you can force quit the application by following these steps:

For iPhone X and later models, as well as iPads running on iOS 12 or a later iOS:
1. Swipe up from the bottom of the Home screen.
2. Swipe left or right until you find the app you want to quit.
3. Swipe the application preview up to force quit it.

For iPhone 8 and older versions:
1. Press the Home button twice to see the list of applications you've recently launched.
2. Swipe left or right until you find the app you want to quit.
3. Swipe the application preview up to force quit it.