DontCross uses google Play Games to display a leaderboard and achievements. You will log in with your personal Google account and will make a Gamer Tag if none has been made before.
The User has a choice to use this feature. When used, all given data is stored by Google and can be deleted in the Google Play Games App.
The final score of the game-mode "Timed" is being saved on an external leaderboard that the user can't see. The score will be compared to others and it will return a percentage on how good the score was.
The score and the phone tag is sent.