If you're seeing a message each time you launch your game that isn't familiar, it is most likely your Apple Game Center nickname, this can easily be changed within your device Settings app.
 
  1. From your device’s Home screen, open your Settings app (gear icon)
  2. Scroll down to select Game Center
  3. On the next screen you will be able to make changes where it says your nickname under Game Center Profile.
 
Apple Support Article: Using Game Center
 
 
If you would like to turn this notification off altogether, this can also be done in your Settings app. Please note: by turning off Game Center, your best time and scoring information will not be saved and cannot be transferred to a new device.
 
1. From your device’s Home screen, open your Settings app (gear icon)
2. Scroll down to select Game Center
3. At the bottom of this page, select Sign Out
 
 
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