diff --git a/binaries/data/mods/public/gui/common/functions_utility.js b/binaries/data/mods/public/gui/common/functions_utility.js
index 2da15e1cae..83990e264a 100644
--- a/binaries/data/mods/public/gui/common/functions_utility.js
+++ b/binaries/data/mods/public/gui/common/functions_utility.js
@@ -59,12 +59,56 @@ function sortNameIgnoreCase(x, y)
  * Escape tag start and escape characters, so users cannot use special formatting.
  * Also limit string length to 256 characters (not counting escape characters).
  */
-function escapeText(text)
+function escapeText(text, limitLength = true)
 {
 	if (!text)
 		return text;
 
-	return text.substr(0, 255).replace(/\\/g, "\\\\").replace(/\[/g, "\\[");
+	if (limitLength)
+		text = text.substr(0, 255);
+
+	return text.replace(/\\/g, "\\\\").replace(/\[/g, "\\[");
+}
+
+function unescapeText(text)
+{
+	if (!text)
+		return text;
+	return text.replace(/\\\\/g, "\\").replace(/\\\[/g, "\[");
+}
+
+/**
+ * Merge players by team to remove duplicate Team entries, thus reducing the packet size of the lobby report.
+ */
+function playerDataToStringifiedTeamList(playerData)
+{
+	let teamList = {};
+
+	for (let pData of playerData)
+	{
+		let team = pData.Team === undefined ? -1 : pData.Team;
+		if (!teamList[team])
+			teamList[team] = [];
+		teamList[team].push(pData);
+		delete teamList[team].Team;
+	}
+
+	return escapeText(JSON.stringify(teamList), false);
+}
+
+function stringifiedTeamListToPlayerData(stringifiedTeamList)
+{
+	let teamList = JSON.parse(unescapeText(stringifiedTeamList));
+	let playerData = [];
+
+	for (let team in teamList)
+		for (let pData of teamList[team])
+		{
+			pData.Team = team;
+			playerData.push(pData);
+		}
+
+	return playerData;
 }
 
 function translateMapTitle(mapTitle)
@@ -226,33 +270,66 @@ function formatPlayerInfo(playerDataArray, playerStates)
 
 	for (let playerData of playerDataArray)
 	{
-		if (playerData == null || playerData.Civ == "gaia")
+		if (playerData == null || playerData.Civ && playerData.Civ == "gaia")
 			continue;
 
 		++playerIdx;
 		let teamIdx = playerData.Team;
 		let isAI = playerData.AI && playerData.AI != "";
-		let playerState = playerStates && playerStates[playerIdx];
+		let playerState = playerStates && playerStates[playerIdx] || playerData.State;
 		let isActive = !playerState || playerState == "active";
 
 		let playerDescription;
 		if (isAI)
 		{
-			if (isActive)
-				// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
-				playerDescription = translate("%(playerName)s (%(civ)s, %(AIdifficulty)s %(AIname)s)");
+			if (playerData.Civ)
+			{
+				if (isActive)
+					// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
+					playerDescription = translate("%(playerName)s (%(civ)s, %(AIdifficulty)s %(AIname)s)");
+				else
+					// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
+					playerDescription = translate("%(playerName)s (%(civ)s, %(AIdifficulty)s %(AIname)s, %(state)s)");
+			}
 			else
-				// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
-				playerDescription = translate("%(playerName)s (%(civ)s, %(AIdifficulty)s %(AIname)s, %(state)s)");
+			{
+				if (isActive)
+					// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
+					playerDescription = translate("%(playerName)s (%(AIdifficulty)s %(AIname)s)");
+				else
+					// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
+					playerDescription = translate("%(playerName)s (%(AIdifficulty)s %(AIname)s, %(state)s)");
+			}
 		}
 		else
 		{
-			if (isActive)
-				// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
-				playerDescription = translate("%(playerName)s (%(civ)s)");
+			if (playerData.Offline)
+			{
+				// Can only occur in the lobby for now, so no strings with civ needed
+				if (isActive)
+					// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
+					playerDescription = translate("%(playerName)s (OFFLINE)");
+				else
+					// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
+					playerDescription = translate("%(playerName)s (OFFLINE, %(state)s)");
+			}
 			else
-				// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
-				playerDescription = translate("%(playerName)s (%(civ)s, %(state)s)");
+			{
+				if (playerData.Civ)
+					if (isActive)
+						// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
+						playerDescription = translate("%(playerName)s (%(civ)s)");
+					else
+						// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
+						playerDescription = translate("%(playerName)s (%(civ)s, %(state)s)");
+				else
+					if (isActive)
+						// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
+						playerDescription = translate("%(playerName)s");
+					else
+						// Translation: Describe a player in a selected game, f.e. in the replay- or savegame menu
+						playerDescription = translate("%(playerName)s (%(state)s)");
+			}
 		}
 
 		// Sort player descriptions by team
@@ -262,7 +339,9 @@ function formatPlayerInfo(playerDataArray, playerStates)
 		playerDescriptions[teamIdx].push(sprintf(playerDescription, {
 			"playerName":
 				'[color="' +
-				rgbToGuiColor(playerData.Color || g_Settings.PlayerDefaults[playerIdx].Color) +
+				(typeof getPlayerColor == 'function' ?
+					(isAI ? "white" : getPlayerColor(playerData.Name)) :
+					rgbToGuiColor(playerData.Color || g_Settings.PlayerDefaults[playerIdx].Color)) +
 				'"]' + escapeText(playerData.Name) + "[/color]",
 
 			"civ":
@@ -283,22 +362,35 @@ function formatPlayerInfo(playerDataArray, playerStates)
 	}
 
 	let teams = Object.keys(playerDescriptions);
+	if (teams.indexOf("observer") > -1)
+		teams.splice(teams.indexOf("observer"), 1);
+
+	let teamDescription = [];
 
 	// If there are no teams, merge all playersDescriptions
 	if (teams.length == 1)
-		return playerDescriptions[teams[0]].join("\n") + "\n";
+		teamDescription.push(playerDescriptions[teams[0]].join("\n"));
 
 	// If there are teams, merge "Team N:" + playerDescriptions
-	return teams.map(team => {
+	else
+		teamDescription = teams.map(team => {
 
-		let teamCaption = team == -1 ?
-			translate("No Team") :
-			sprintf(translate("Team %(team)s"), { "team": +team + 1 });
+			let teamCaption = team == -1 ?
+				translate("No Team") :
+				sprintf(translate("Team %(team)s"), { "team": +team + 1 });
 
-		// Translation: Describe players of one team in a selected game, f.e. in the replay- or savegame menu or lobby
-		return sprintf(translate("%(team)s:\n%(playerDescriptions)s"), {
-			"team": '[font="sans-bold-14"]' + teamCaption + "[/font]",
-			"playerDescriptions": playerDescriptions[team].join("\n")
+			// Translation: Describe players of one team in a selected game, f.e. in the replay- or savegame menu or lobby
+			return sprintf(translate("%(team)s:\n%(playerDescriptions)s"), {
+				"team": '[font="sans-bold-14"]' + teamCaption + "[/font]",
+				"playerDescriptions": playerDescriptions[team].join("\n")
+			});
 		});
-	}).join("\n\n");
+
+	if (playerDescriptions.observer)
+		teamDescription.push(sprintf(translate("%(team)s:\n%(playerDescriptions)s"), {
+			"team": '[font="sans-bold-14"]' + translatePlural("Observer", "Observers", playerDescriptions.observer.length) + "[/font]",
+			"playerDescriptions": playerDescriptions.observer.join("\n")
+		}));
+
+	return teamDescription.join("\n\n");
 }
diff --git a/binaries/data/mods/public/gui/gamesetup/gamesetup.js b/binaries/data/mods/public/gui/gamesetup/gamesetup.js
index 6cc00a4526..3b160211ad 100644
--- a/binaries/data/mods/public/gui/gamesetup/gamesetup.js
+++ b/binaries/data/mods/public/gui/gamesetup/gamesetup.js
@@ -676,10 +676,11 @@ function handleReadyMessage(message)
  */
 function handleGamestartMessage(message)
 {
+	// Immediately inform the lobby server instead of waiting for the load to finish
 	if (g_IsController && Engine.HasXmppClient())
 	{
-		let playerNames = Object.keys(g_PlayerAssignments).map(guid => g_PlayerAssignments[guid].name);
-		Engine.SendChangeStateGame(playerNames.length, playerNames.join(", "));
+		let clients = formatClientsForStanza();
+		Engine.SendChangeStateGame(clients.connectedPlayers, clients.list);
 	}
 
 	Engine.SwitchGuiPage("page_loading.xml", {
@@ -1498,7 +1499,7 @@ function updateMapDescription()
 			translate(g_GameAttributes.settings.Description) :
 			translate("Sorry, no description available.");
 
-	let victoryIdx = g_VictoryConditions.Name.indexOf(g_GameAttributes.settings.GameType);
+	let victoryIdx = g_VictoryConditions.Name.indexOf(g_GameAttributes.settings.GameType || g_VictoryConditions.Default);
 	let victoryTitle;
 
 	if (victoryIdx == -1)
@@ -1935,6 +1936,34 @@ function resetReadyData()
 		setReady(false, false);
 }
 
+/**
+ * Send a list of playernames and distinct between players and observers.
+ * Don't send teams, AIs or anything else until the game was started.
+ * The playerData format from g_GameAttributes is kept to reuse the GUI function presenting the data.
+ */
+function formatClientsForStanza()
+{
+	let connectedPlayers = 0;
+	let playerData = [];
+
+	for (let guid in g_PlayerAssignments)
+	{
+		let pData = { "Name": g_PlayerAssignments[guid].name };
+
+		if (g_GameAttributes.settings.PlayerData[g_PlayerAssignments[guid].player - 1])
+			++connectedPlayers;
+		else
+			pData.Team = "observer";
+
+		playerData.push(pData);
+	}
+
+	return {
+		"list": playerDataToStringifiedTeamList(playerData),
+		"connectedPlayers": connectedPlayers
+	};
+}
+
 /**
  * Send the relevant gamesettings to the lobbybot.
  */
@@ -1948,7 +1977,7 @@ function sendRegisterGameStanza()
 
 	let mapSize = g_GameAttributes.mapType == "random" ? Engine.GetGUIObjectByName("mapSize").list_data[selectedMapSize] : "Default";
 	let victoryCondition = Engine.GetGUIObjectByName("victoryCondition").list[selectedVictoryCondition];
-	let playerNames = Object.keys(g_PlayerAssignments).map(guid => g_PlayerAssignments[guid].name).sort();
+	let clients = formatClientsForStanza();
 
 	let stanza = {
 		"name": g_ServerName,
@@ -1958,9 +1987,9 @@ function sendRegisterGameStanza()
 		"mapSize": mapSize,
 		"mapType": g_GameAttributes.mapType,
 		"victoryCondition": victoryCondition,
-		"nbp": Object.keys(g_PlayerAssignments).length || 1,
-		"tnbp": g_GameAttributes.settings.PlayerData.length,
-		"players": playerNames.join(", ")
+		"nbp": clients.connectedPlayers,
+		"maxnbp": g_GameAttributes.settings.PlayerData.length,
+		"players": clients.list,
 	};
 
 	// Only send the stanza if the relevant settings actually changed
diff --git a/binaries/data/mods/public/gui/lobby/lobby.js b/binaries/data/mods/public/gui/lobby/lobby.js
index f1e18bb735..120155e11b 100644
--- a/binaries/data/mods/public/gui/lobby/lobby.js
+++ b/binaries/data/mods/public/gui/lobby/lobby.js
@@ -285,14 +285,14 @@ function filterGame(game)
 		return true;
 
 	if (playersNumberFilter.selected != 0 &&
-	    game.tnbp != playersNumberFilter.list_data[playersNumberFilter.selected])
+	    game.maxnbp != playersNumberFilter.list_data[playersNumberFilter.selected])
 		return true;
 
 	if (mapTypeFilter.selected != 0 &&
 	    game.mapType != mapTypeFilter.list_data[mapTypeFilter.selected])
 		return true;
 
-	if (!showFullFilter.checked && game.tnbp <= game.nbp)
+	if (!showFullFilter.checked && game.maxnbp <= game.nbp)
 		return true;
 
 	return false;
@@ -546,8 +546,8 @@ function updateGameList()
 			break;
 		case 'nPlayers':
 			// Compare playercount ratio
-			sortA = a.nbp * b.tnbp;
-			sortB = b.nbp * a.tnbp;
+			sortA = a.nbp * b.maxnbp;
+			sortB = b.nbp * a.maxnbp;
 			break;
 		case 'status':
 		default:
@@ -582,7 +582,7 @@ function updateGameList()
 		list_mapName.push(translateMapTitle(game.niceMapName));
 		list_mapSize.push(translateMapSize(game.mapSize));
 		list_mapType.push(g_MapTypes.Title[mapTypeIdx] || "");
-		list_nPlayers.push(game.nbp + "/" + game.tnbp);
+		list_nPlayers.push(game.nbp + "/" + game.maxnbp);
 		list.push(gameName);
 		list_data.push(i);
 	}
@@ -618,10 +618,10 @@ function updateGameSelection()
 	Engine.GetGUIObjectByName("sgNbPlayers").caption = sprintf(
 		translate("Players: %(current)s/%(total)s"), {
 			"current": game.nbp,
-			"total": game.tnbp
+			"total": game.maxnbp
 		});
 
-	Engine.GetGUIObjectByName("sgPlayersNames").caption = game.players;
+	Engine.GetGUIObjectByName("sgPlayersNames").caption = formatPlayerInfo(stringifiedTeamListToPlayerData(game.players));
 	Engine.GetGUIObjectByName("sgMapSize").caption = translateMapSize(game.mapSize);
 
 	let mapTypeIdx = g_MapTypes.Name.indexOf(game.mapType);
@@ -653,7 +653,7 @@ function joinButton()
 
 	let username = g_UserRating ? g_Username + " (" + g_UserRating + ")" : g_Username;
 
-	if (game.state == "init" || game.players.split(", ").indexOf(username) > -1)
+	if (game.state == "init" || stringifiedTeamListToPlayerData(game.players).some(player => player.Name == username))
 		joinSelectedGame();
 	else
 		messageBox(
diff --git a/binaries/data/mods/public/gui/session/messages.js b/binaries/data/mods/public/gui/session/messages.js
index 5392657cbf..13f2838d76 100644
--- a/binaries/data/mods/public/gui/session/messages.js
+++ b/binaries/data/mods/public/gui/session/messages.js
@@ -250,6 +250,7 @@ var g_NotificationsTypes =
 			"resign": !!notification.resign
 		});
 		playerFinished(player, false);
+		sendLobbyPlayerlistUpdate();
 	},
 	"won": function(notification, player)
 	{
@@ -259,6 +260,7 @@ var g_NotificationsTypes =
 			"player": player
 		});
 		playerFinished(player, true);
+		sendLobbyPlayerlistUpdate();
 	},
 	"diplomacy": function(notification, player)
 	{
@@ -541,13 +543,7 @@ function handlePlayerAssignmentsMessage(message)
 	});
 
 	updateChatAddressees();
-
-	// Update lobby gamestatus
-	if (g_IsController && Engine.HasXmppClient())
-	{
-		let players = Object.keys(g_PlayerAssignments).map(guid => g_PlayerAssignments[guid].name);
-		Engine.SendChangeStateGame(Object.keys(g_PlayerAssignments).length, players.join(", "));
-	}
+	sendLobbyPlayerlistUpdate();
 }
 
 function onClientJoin(guid)
diff --git a/binaries/data/mods/public/gui/session/session.js b/binaries/data/mods/public/gui/session/session.js
index 245ff19335..d52dc38deb 100644
--- a/binaries/data/mods/public/gui/session/session.js
+++ b/binaries/data/mods/public/gui/session/session.js
@@ -15,7 +15,7 @@ const g_Ambient = [ "audio/ambient/dayscape/day_temperate_gen_03.ogg" ];
 /**
  * Map, player and match settings set in gamesetup.
  */
-var g_GameAttributes;
+const g_GameAttributes = Object.freeze(Engine.GetInitAttributes());
 
 /**
  * Is this user in control of game settings (i.e. is a network server, or offline player).
@@ -225,8 +225,6 @@ function init(initData, hotloadData)
 		return;
 	}
 
-	g_GameAttributes = Engine.GetInitAttributes();
-
 	if (initData)
 	{
 		g_IsNetworked = initData.isNetworked;
@@ -289,8 +287,8 @@ function init(initData, hotloadData)
 	if (hotloadData)
 		g_Selection.selected = hotloadData.selection;
 
+	sendLobbyPlayerlistUpdate();
 	onSimulationUpdate();
-
 	setTimeout(displayGamestateNotifications, 1000);
 
 	// Report the performance after 5 seconds (when we're still near
diff --git a/binaries/data/mods/public/gui/session/utility_functions.js b/binaries/data/mods/public/gui/session/utility_functions.js
index e47dac4a1f..36a4552d67 100644
--- a/binaries/data/mods/public/gui/session/utility_functions.js
+++ b/binaries/data/mods/public/gui/session/utility_functions.js
@@ -131,3 +131,61 @@ function resourcesToAlphaMask(neededResources)
 	alpha = alpha > 125 ? 125 : alpha;
 	return "color:255 0 0 " + alpha;
 }
+
+/**
+ * Send the current list of players, teams, AIs, observers and defeated/won and offline states to the lobby.
+ * The playerData format from g_GameAttributes is kept to reuse the GUI function presenting the data.
+ */
+function sendLobbyPlayerlistUpdate()
+{
+	if (!g_IsController || !Engine.HasXmppClient())
+		return;
+
+	// Extract the relevant player data and minimize packet load
+	let minPlayerData = [];
+	for (let playerID in g_GameAttributes.settings.PlayerData)
+	{
+		if (+playerID == 0)
+			continue;
+
+		let pData = g_GameAttributes.settings.PlayerData[playerID];
+
+		let minPData = { "Name": pData.Name };
+
+		if (g_GameAttributes.settings.LockTeams)
+			minPData.Team = pData.Team;
+
+		if (pData.AI)
+		{
+			minPData.AI = pData.AI;
+			minPData.AIDiff = pData.AIDiff;
+		}
+
+		if (g_Players[playerID].offline)
+			minPData.Offline = true;
+
+		// Whether the player has won or was defeated
+		let state = g_Players[playerID].state;
+		if (state != "active")
+			minPData.State = state;
+
+		minPlayerData.push(minPData);
+	}
+
+	// Add observers
+	let connectedPlayers = 0;
+	for (let guid in g_PlayerAssignments)
+	{
+		let pData = g_GameAttributes.settings.PlayerData[g_PlayerAssignments[guid].player];
+
+		if (pData)
+			++connectedPlayers;
+		else
+			minPlayerData.push({
+				"Name": g_PlayerAssignments[guid].name,
+				"Team": "observer"
+			});
+	}
+
+	Engine.SendChangeStateGame(connectedPlayers, playerDataToStringifiedTeamList(minPlayerData));
+}
diff --git a/source/lobby/XmppClient.cpp b/source/lobby/XmppClient.cpp
index f48881ee75..10a2f28818 100644
--- a/source/lobby/XmppClient.cpp
+++ b/source/lobby/XmppClient.cpp
@@ -502,7 +502,7 @@ void XmppClient::GUIGetGameList(ScriptInterface& scriptInterface, JS::MutableHan
 	JSAutoRequest rq(cx);
 
 	scriptInterface.Eval("([])", ret);
-	const char* stats[] = { "name", "ip", "port", "state", "nbp", "tnbp", "players", "mapName", "niceMapName", "mapSize", "mapType", "victoryCondition" };
+	const char* stats[] = { "name", "ip", "port", "state", "nbp", "maxnbp", "players", "mapName", "niceMapName", "mapSize", "mapType", "victoryCondition" };
 	for(const glooxwrapper::Tag* const& t : m_GameList)
 	{
 		JS::RootedValue game(cx);
diff --git a/source/tools/XpartaMuPP/XpartaMuPP.py b/source/tools/XpartaMuPP/XpartaMuPP.py
index f0dfdb9c23..f3e2ff83a7 100644
--- a/source/tools/XpartaMuPP/XpartaMuPP.py
+++ b/source/tools/XpartaMuPP/XpartaMuPP.py
@@ -301,12 +301,12 @@ class GameList():
     if JID in self.gameList:
       if self.gameList[JID]['nbp-init'] > data['nbp']:
         logging.debug("change game (%s) state from %s to %s", JID, self.gameList[JID]['state'], 'waiting')
-        self.gameList[JID]['nbp'] = data['nbp']
         self.gameList[JID]['state'] = 'waiting'
       else:
         logging.debug("change game (%s) state from %s to %s", JID, self.gameList[JID]['state'], 'running')
-        self.gameList[JID]['nbp'] = data['nbp']
         self.gameList[JID]['state'] = 'running'
+      self.gameList[JID]['nbp'] = data['nbp']
+      self.gameList[JID]['players'] = data['players']
 
 ## Class which manages different game reports from clients ##
 ##   and calls leaderboard functions as appropriate.       ##