No, it is not.

Please be warned that even if the Google Play/Game Center sign in notification shows up after starting the game, it doesn't mean that your account has been linked!

       
To properly link your account to Google Play or Apple Game Center, open the Menu from the Home screen and select [Account Transfer].

For more details, please refer to the following FAQs:

• Transferring between Android devices
• Transferring between iOS devices

*Please note that the option to link to Google Play or the Game Center may not appear depending on your app settings.

If you delete the app without linking your account, your play data will be lost forever, so please be careful!