1. Please make sure you have updated the game to the latest version.
2. Make sure your device meets the minimum system requirements for gaming. Currently, the minimum device and operating system requirements are as follows (they may change in the future as we keep optimizing the game):
Apple devices with iOS 12.0 and later, not including iPhone 6 Plus and earlier, iPad 4 and earlier, iPad Mini 3 and earlier, iPad Air 2 and earlier, iPod Touch 7 and earlier.
Android devices with Android 5 and later, with at least 2GB RAM.
At least 2GB free space.
Stable internet connection.