diff --git a/OpenRA.Game/Game.cs b/OpenRA.Game/Game.cs
index ae396b2131..8e1bd50801 100644
--- a/OpenRA.Game/Game.cs
+++ b/OpenRA.Game/Game.cs
@@ -163,28 +163,7 @@ namespace OpenRA
 
 		internal static void SyncLobbyInfo(string data)
 		{
-			var session = new Session();
-			session.GlobalSettings.Mods = Settings.InitialMods;
-
-			var ys = MiniYaml.FromString(data);
-			foreach (var y in ys)
-			{
-				if (y.Key == "GlobalSettings")
-				{
-					FieldLoader.Load(session.GlobalSettings, y.Value);
-					continue;
-				}
-
-				int index;
-				if (!int.TryParse(y.Key, out index))
-					continue;	// not a player.
-
-				var client = new Session.Client();
-				FieldLoader.Load(client, y.Value);
-				session.Clients.Add(client);
-			}
-
-			LobbyInfo = session;
+			LobbyInfo = Session.Deserialize(data);
 
 			if( !world.GameHasStarted )
 				world.SharedRandom = new XRandom( LobbyInfo.GlobalSettings.RandomSeed );
diff --git a/OpenRA.Game/Network/Session.cs b/OpenRA.Game/Network/Session.cs
index 34b0a2da57..7c0c970e68 100644
--- a/OpenRA.Game/Network/Session.cs
+++ b/OpenRA.Game/Network/Session.cs
@@ -10,16 +10,14 @@
 
 using System.Collections.Generic;
 using System.Drawing;
+using OpenRA.FileFormats;
 
 namespace OpenRA.Network
 {
-	// todo: ship most of this back to the Game assembly;
-	// it was only in FileFormats due to the original server model,
-	// in a sep. process.
-
 	public class Session
 	{
 		public List<Client> Clients = new List<Client>();
+		public List<Slot> Slots = new List<Slot>();
 		public Global GlobalSettings = new Global();
 
 		public enum ClientState
@@ -40,6 +38,15 @@ namespace OpenRA.Network
 			public int Team;
 		}
 
+		public class Slot
+		{
+			public int Index;
+			public string Bot;	// trait name of the bot to initialize in this slot, or null otherwise.
+			public bool Closed;	// host has explicitly closed this slot.
+			
+			// todo: more stuff?
+		}
+
 		public class Global
 		{
 			public string Map;
@@ -49,5 +56,49 @@ namespace OpenRA.Network
 			public bool LockTeams = false;	// don't allow team changes after game start.
 			public bool AllowCheats = false;
 		}
+
+		public string Serialize()
+		{
+			var clientData = new Dictionary<string, MiniYaml>();
+
+			foreach (var client in Clients)
+				clientData["Client@{0}".F(client.Index)] = FieldSaver.Save(client);
+
+			foreach (var slot in Slots)
+				clientData["Slot@{0}".F(slot.Index)] = FieldSaver.Save(slot);
+
+			clientData["GlobalSettings"] = FieldSaver.Save(GlobalSettings);
+
+			return clientData.WriteToString();
+		}
+
+		public static Session Deserialize(string data)
+		{
+			var session = new Session();
+			session.GlobalSettings.Mods = Game.Settings.InitialMods;
+
+			var ys = MiniYaml.FromString(data);
+			foreach (var y in ys)
+			{
+				var yy = y.Key.Split('@');
+
+				switch( yy[0] )
+				{
+					case "GlobalSettings":
+						FieldLoader.Load(session.GlobalSettings, y.Value);
+						break;
+
+					case "Client":
+						session.Clients.Add(FieldLoader.Load<Session.Client>(y.Value));
+						break;
+
+					case "Slot":
+						session.Slots.Add(FieldLoader.Load<Session.Slot>(y.Value ));
+						break;
+				}
+			}
+
+			return session;
+		}
 	}
 }
diff --git a/OpenRA.Game/Server/ProtocolVersion.cs b/OpenRA.Game/Server/ProtocolVersion.cs
index 99aeaf4916..b187d4ddfb 100644
--- a/OpenRA.Game/Server/ProtocolVersion.cs
+++ b/OpenRA.Game/Server/ProtocolVersion.cs
@@ -13,6 +13,6 @@ namespace OpenRA.Server
 	public static class ProtocolVersion
 	{
 		// you *must* increment this whenever you make an incompatible protocol change
-		public static readonly int Version = 5;
+		public static readonly int Version = 6;
 	}
 }
diff --git a/OpenRA.Game/Server/Server.cs b/OpenRA.Game/Server/Server.cs
index ceb7ab8eb0..a8e6e723b9 100644
--- a/OpenRA.Game/Server/Server.cs
+++ b/OpenRA.Game/Server/Server.cs
@@ -450,14 +450,8 @@ namespace OpenRA.Server
 
 		static void SyncLobbyInfo()
 		{
-			var clientData = lobbyInfo.Clients.ToDictionary(
-				a => a.Index.ToString(),
-				a => FieldSaver.Save(a));
-
-			clientData["GlobalSettings"] = FieldSaver.Save(lobbyInfo.GlobalSettings);
-
 			DispatchOrders(null, 0,
-				new ServerOrder("SyncInfo", clientData.WriteToString()).Serialize());
+				new ServerOrder("SyncInfo", lobbyInfo.Serialize()).Serialize());
 
 			PingMasterServer();
 		}