Google Play game services, the backend that powers online features for many Android games, is expanding significantly to iOS. In an announcement timed for the Game Developers Conference this week, Google says it's bringing turn-based and real-time multiplayer capabilities to iOS. Should developers choose to integrate the service with their games, they'll be able to enable gamers with Android and iOS devices to play against each other cross-platform.

Play Games already supports iOS through a plug-in for the Unity game engine that supports achievements and leaderboards, and that plug-in will be updated soon adding the multiplayer element. An early version of a separate SDK for non-Unity games is also being released, but at launch it won't support multiplayer gaming. As we exclusively revealed recently, Microsoft is planning to expand Xbox Live to mobile platforms in order to facilitate multiplayer matchmaking, achievements, and friends lists. Xbox Live already powers some games on Microsoft's Windows Phone platform, but the new mobile push will focus on iOS and Android.

Both Google and Microsoft want to power cross-platform gaming

Google's decision to expand multiplayer capabilities to iOS, coupled with Microsoft's anticipated announcement, could signal a change in the way the big three mobile operating systems approach gaming. Until now each company did its own thing — iOS has GameCenter, Android has Google Play game services, and Windows Phone has Xbox Live — while third parties like Facebook power the social and leaderboard aspects of popular games like Candy Crush Saga.

It's early days for Google Play game services' cross-platform expansion. Although it's a popular game engine, a Unity plug-in won't cut it for many developers, and its non-Unity efforts are still in the early stages of development. We expect to hear more about Google's new cross-platform gaming this week at GDC. The company says "most" of the features will become available on Tuesday March 18th, and it's holding a developer day at the conference to try and persuade game makers to use its services over other companies'.