Google Play Games update will bring quests, saves, and advanced graphics soon
Additionally, the Android L Version release brings new platform capabilities, such as support for OpenGL ES 3.1 (which will enable compute shaders, stencil textures, more interesting physics and graphical effects), Android Extension Pack (a new set of extensions to OpenGL ES, including tessellation and geometry shaders), and Google Gamepad standards (controller compatibility on Android, Chrome, and Chromebooks).
The changes to Google Play Games will be rolling out with updates to Google Play Service and the Play Games App over the next few weeks. Meanwhile, the Android L-release changes are present in the announced developer preview.
source: Android Developers Blog