What is play-games-plugin-for-unity?

The Google Play Games plugin for Unity is an open-source library that lets game developers add Google Play Games features to games built with the Unity game engine. Instead of integrating directly with Google's Android APIs, which requires writing native Android code, developers can call Play Games functions from within Unity using C# or UnityScript. The plugin connects to Unity's built-in social interface, meaning you use familiar Unity patterns rather than learning a separate API. Through the plugin, a game can sign players in with their Google account, unlock or track achievements, post scores to leaderboards, save and load game progress to Google's cloud save system, and display the standard built-in achievement and leaderboard screens that Google provides. There is also support for nearby connections, which allows devices near each other to communicate directly for local multiplayer. Setup is done through Unity's editor interface rather than by manually editing Android configuration files, which keeps the integration process straightforward. One important note: this plugin only works for Android. Support for iOS was removed because Google deprecated Play Games services for iOS in 2017. If you are building a cross-platform game and want Play Games features, you will only get them on the Android version. The plugin size can be reduced before shipping by using Proguard (an Android code shrinking tool) to strip out the parts of the Play Games code your game does not use. Unity's own managed code stripping can be used alongside this for further size reduction. For setup instructions and API details, a developer guide is available on the Android developer documentation site.