Looking for logging into the Play Services Server Client site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Play Services Server Client site. After that you can login as usual with your login credentials.
https://developers.google.com/identity/sign-in/web/server-side-flow
https://developers.google.com/games/services/web/serverlogin
https://developers.google.com/identity/protocols/OAuth2ServiceAccount
https://stackoverflow.com/questions/17858828/implement-google-login-in-android-client-server-app
https://api.playfab.com/documentation/client/method/LoginWithGoogleAccount
https://api.playfab.com/docs/tutorials/landing-players/sign-in-with-google
https://firebase.google.com/docs/auth/android/google-signin
https://firebase.google.com/docs/auth/unity/play-games
https://www.youtube.com/watch?v=VpRjvQEHF3E
https://android-developers.googleblog.com/2016/03/registering-oauth-clients-for-google.html
https://github.com/googleapis/google-api-java-client
https://medium.com/@p.tournaris/android-improving-sign-in-experience-with-google-sign-in-and-smartlock-f0bfd789602a
https://azure.microsoft.com/en-us/blog/logging-in-with-google-microsoft-and-facebook-sdks-to-azure-mobile-services/