Regardless of the fact that Google+ has been floundering for the last few years, the social network has remained a requirement to use Google services like YouTube and Google Play Games. It seems Google has learned its lesson and has plans to remove Google+ account requirements from most of Google’s services.
This week, changes to Google Play Games’ permissions aim to simplify the login process and remove the requirement for a Google+ account. Once these changes come into effect, players will no longer be required to sign in once per game, but only once per account (though auto sign-in can be turned off).
In cases where users already have a player ID connected to their Google+ profile, they will continue to use this ID, but new users will receive a new player ID that isn’t connected to Google+. According to an Android Developer Blog explaining the changes, there should be no issues for the vast majority of games, even if developers take no action.
Source: Android Developers Blog