You probably don't use the Google Play Games app (I sure can't remember the last time I did), but many games on the Play Store use its API. Developers can use the Play Games API to save game data to the cloud, add achievements, and integrate analytics.

Today on the Android Developers Blog, Google announced it would shut down several features in Play Games Services. These include Gifts, Requests, and Quests. All three features will be supported until March 31st, 2018, so developers have a while to find alternatives.

Other features like achievements and multiplayer will not be affected. You can find more information at the source link below.