It was announced a few weeks ago that Google Play Games would be dropping its Google+ integration and opting for another method for profiles. At the time, Google hadn't announced how that would work, or when it would happen. However it's happening today. In a blog post on their Android blog, Google announces that Google Play Games will be ditching Google+ integration and instead will be doing Gamer ID Profiles, in an update that is rolling out beginning today.
With the new Gamer ID Profiles, users will be able to pick a nickname for themselves as well as set a profile picture. Google also is noting that you can choose to link your Gamer ID to your Google account or remain anonymous. Now these changes do not affect the way that games save your progress through Google Play Games. So that's a relief. You'll be able to search for other players using their Gamer ID, and if they have their account linked up, you'll be able to search by their email. Additionally, you don't need a Google account at all to use Google Play Games now (however you will need it to be able to download games from the Play Store still).
Product Manager of Google Play Games, Ben Frenkel notes that the changes here are more about allowing gamers be who they want to be. Instead of using their real names, they can use another name. Including their screen names from other games on other platforms. Don't think that now where you can create any nickname for your Gamer ID profile, that you'll be able to abuse Play Games, as Frenkel states there is a pretty robust spam filter and abuse filter put in place with the Gamer ID system.
When you first download and open up Google Play Games, you'll be opted to set up your Gamer ID profile. It's pretty quick and easy to do. We just set ours up in a matter of minutes and are able to play across the multitude of games available supporting Google Play Games already. Additionally, this update brings auto-sign in allowing you to sign in once per account instead of on a per game basis.