I recently completed a project in multiplayer. Photon and PlayFab are used for multiplayer gameplay and storing the player data on the server. Auto-login with the Google-Play-Game ID as a username on Android and a random username generated in the iPhone build. The player can do a lot of things in the game like he can search for the player, add the player to the friend list, see the friend list, remove a friend, invite a friend to join his room, accept or reject the invite, multiplayer gameplay with their friend and with random players.