Incorrect aspect ratio
If the aspect ratio of the game does not use the full screen of your phone, please check if your device has a "Full-Screen mode" setting. If so, please enable this option for Gods&Glory.
You should be able to find this option, if available, in the settings of your phone.
Soft reset
Hold the Power and Volume Up buttons for 7-10 seconds. Your device should then restart.
Clear cache
You can clear the cache of your Android device under:
Settings → Apps/Applications → Select App → Storage → Clear Cache.
The arrangement of the settings depends on the manufacturer of your phone, but you should be able to find a list with all installed apps in the settings, just the name and the exact location is different.