Why was my Game Center app deleted?
Apple has opted to remove the Game Center app in iOS 10. Some iOS games will still include Game Center features, such as Leaderboards and the ability to send gaming invites. All Game Center features will now be handled within specific apps that utilize Apple's GameKit, instead of being handled through the standalone Game Center app.
Game Center was original launched in iOS 4.0 on September 8, 2010. The stock app acted as a multiplayer social gaming network for iOS users. The app allowed users to connect with friends, send friend requests, and keep track of Leaderboards and achievements. Players could also use the app to organize online multiplayer games.