Reordered the MessageTypes and added space for clarity (and ensured none are serialized). Broke up the GameManager OnReceiveMessage a bit for readability.

Assets/Scripts/Game/GameManager.cs

         /// </summary>
         public void OnReceiveMessage(MessageType type, object msg)
         {
-            if (type == MessageType.RenameRequest)
-            {   m_localUser.DisplayName = (string)msg;
-            }
-            else if (type == MessageType.CreateLobbyRequest)
+            if (type == MessageType.CreateLobbyRequest)
             {
                 var createLobbyData = (LocalLobby)msg;
                 LobbyAsyncRequests.Instance.CreateLobbyAsync(createLobbyData.LobbyName, createLobbyData.MaxPlayerCount, createLobbyData.Private, m_localUser, (r) =>
                     },
                     m_lobbyColorFilter);
             }
-            else if (type == MessageType.ChangeGameState)
-            {   SetGameState((GameState)msg);
+            else if (type == MessageType.QuickJoin)
+            {
+                LobbyAsyncRequests.Instance.QuickJoinLobbyAsync(m_localUser, m_lobbyColorFilter, (r) =>
+                    {   lobby.ToLocalLobby.Convert(r, m_localLobby);
+                        OnJoinedLobby();
+                    },
+                    OnFailedJoin);
+            }
+
+            else if (type == MessageType.RenameRequest)
+            {   m_localUser.DisplayName = (string)msg;
             }
             else if (type == MessageType.ClientUserApproved)
             {   ConfirmApproval();
             else if (type == MessageType.LobbyUserStatus)
             {   m_localUser.UserStatus = (UserStatus)msg;
             }
+
             else if (type == MessageType.StartCountdown)
             {   m_localLobby.State = LobbyState.CountDown;
             }
             else if (type == MessageType.CompleteCountdown)
             {   if (m_relayClient is RelayUtpHost)
                     (m_relayClient as RelayUtpHost).SendInGameState();
+            }
+
+            else if (type == MessageType.ChangeGameState)
+            {   SetGameState((GameState)msg);
             }
             else if (type == MessageType.ConfirmInGameState)
             {   m_localUser.UserStatus = UserStatus.InGame;
             {   m_localLobby.State = LobbyState.Lobby;
                 SetUserLobbyState();
-            }
-            else if (type == MessageType.QuickJoin)
-            {
-                LobbyAsyncRequests.Instance.QuickJoinLobbyAsync(m_localUser, m_lobbyColorFilter, (r) =>
-                    {   lobby.ToLocalLobby.Convert(r, m_localLobby);
-                      OnJoinedLobby();
-                    },
-                    OnFailedJoin);
-			}
-            else if (type == MessageType.SetPlayerSound)
-            {
-                var playerSound = (LobbyUserAudio)msg;
             }
         }
 

Assets/Scripts/Infrastructure/Messenger.cs

         JoinLobbyRequest = 2,
         CreateLobbyRequest = 3,
         QueryLobbies = 4,
-        ChangeGameState = 5,
-        LobbyUserStatus = 6,
-        UserSetEmote = 7,
-        EndGame = 8,
-        StartCountdown = 9,
-        CancelCountdown = 10,
-        ConfirmInGameState = 11,
-        DisplayErrorPopup = 12,
-        SetPlayerSound = 13,
-        QuickJoin = 14,
-        ClientUserApproved = 15,
-        ClientUserSeekingDisapproval = 16,
-        CompleteCountdown = 17,
+        QuickJoin = 5,
+
+        ChangeGameState = 100,
+        ConfirmInGameState = 101,
+        LobbyUserStatus = 102,
+        UserSetEmote = 103,
+        ClientUserApproved = 104,
+        ClientUserSeekingDisapproval = 105,
+        EndGame = 106,
+
+        StartCountdown = 200,
+        CancelCountdown = 201,
+        CompleteCountdown = 202,
+
+        DisplayErrorPopup = 300,
     }
 
     /// <summary>