I know that many of you asked about retrieving Access Token from Google Play Games in UE4. After some research and investigating issue, I’ve just made pull request with this functionality added.
Access Token allow you calling any REST API for Google Play Games so it’s a huge deal! More info: https://developers.google.com/games/services/web/gettingstarted
You can wait when Epic merge these changes into engine or grab it now from GitHub repository: https://github.com/EpicGames/UnrealEngine/pull/2372
If you have any questions, ask me