If you're an avid gamer on Android, get ready to see quite a bit fewer of those pesky Google+ sign-in prompts. Google is rearranging things a bit in the Games API to cut back on permission dialogs and authorization requests so users have an easier time getting straight into the action. The changes should also allow game developers to take advantage of Google's Games API and services like cloud sync without asking users to trust them with account details and potentially sensitive information.
With the new model, users will only be asked to sign in once per account—just to set it up—and every subsequent new game that runs can sign in automatically. The key change is that the Games API no longer requests access to a user's Google+ account in order to access the Games-specific services. Instead, a distinct player ID is created to maintain a degree of separation and privacy. The only time a prompt should appear is if a game specifically asks for permissions to access the social account, which users are still free to restrict or deny if they see fit. Automatic sign-in can also be disabled in the Settings screen of the Play Games app if desired. (Note: this setting doesn't appear to be available yet, but it's probably coming with an update to either Play Games or Play Services.)
Game developers should look through Google's blog post for advice and discussion about potential issues related to these changes. The advice largely centers around removing unnecessary requests for the Google+ scope if a game doesn't actually use it. There are also a few notes about the player ID and how it's meant to be used, which may cause some problems if it has been misused in some apps.
Since it is once again en vogue to compare and contrast relatively innocuous details about competing mobile platforms, it's worth mentioning Apple's Game Center has always used automatic sign-in. Of course, the difference is Play Games is segregating the social networking element of Google+ behind a confirmation dialog because many people consider it a privacy issue, while Game Center is already a kind of social network that isn't considered invasive because nobody really looks at or uses it. (At least that's what I've been told by every iOS user I've ever asked.)
No timeframe has been given to specify when these changes will come into effect. At a minimum, an update to the Play Services apk will probably roll out to all users. An update to the Play Games app is also likely. It's not clear if an updated SDK will be necessary, but it doesn't sound like it.
- Android Developers Blog
Alternate Title: Google Streamlines Play Games API, Everybody Groans At Another Round Of Declarations That Google+ Is Dead