DumaOS is designed to work with console and PC games. Compatibility with mobile games cannot be guaranteed, as many mobile games used centralised servers that cannot be bypassed.
If you would like to attempt filtering a mobile game, this can be done, but is not officially supported or tested by Netduma.
Change your phone's device type to Xbox or PlayStation so that DumaOS sees it as a console. Now add the device to Geo-Filter, and select the "Choose Manually" option. Now choose Filtering Mode. At this point, all UDP traffic from the phone is being filtered, so you can start up the game and see if it filters.
This filtering may affect other functionality of the phone, so if you find that you're having problems connecting to anything on the phone, either remove the device from Geo-Filter, or disconnect it from wifi.