--- a/rts/Net/GameServer.cpp
+++ b/rts/Net/GameServer.cpp
@@ -70,6 +70,7 @@
 CONFIG(int, ServerSleepTime).defaultValue(5).description("Number of milliseconds to sleep per tick for the server thread. Lower values have marginally higher CPU load, while high values can introduce additional latency.");
 CONFIG(int, SpeedControl).defaultValue(1).minimumValue(1).maximumValue(2)
 	.description("Sets how server adjusts speed according to player's load (CPU), 1: use average, 2: use highest");
+CONFIG(bool, WebbarRequireAllPlayers).defaultValue(false).description("Require every configured participant to finish loading before starting a private WebBAR match.");
 CONFIG(bool, AllowSpectatorJoin).defaultValue(true).dedicatedValue(false).description("allow any unauthenticated clients to join as spectator with any name, name will be prefixed with ~");
 CONFIG(bool, WhiteListAdditionalPlayers).defaultValue(true);
 CONFIG(bool, ServerRecordDemos).defaultValue(false).dedicatedValue(true);
@@ -2191,6 +2192,7 @@
 void CGameServer::CheckForGameStart(bool forced)
 {
 	assert(!gameHasStarted);
+	const bool requireAllPlayers = configHandler->GetBool("WebbarRequireAllPlayers");
 	bool allReady = true;
 	// anyReady is needed for the case when *nodoby* is connected to the server yet, so in principle
 	// everybody that is, is ready. Without that logic the game will start after XX seconds (see below)
@@ -2200,6 +2202,11 @@
 	for (size_t a = static_cast<size_t>(myGameSetup->numDemoPlayers); a < players.size(); a++) {
 		if (players[a].isFromDemo)
 			continue;
+
+		if (requireAllPlayers && players[a].myState != GameParticipant::INGAME) {
+			allReady = false;
+			break;
+		}
 
 		if (players[a].myState == GameParticipant::UNCONNECTED && serverStartTime + spring_secs(30) < spring_gettime()) {
 			// autostart the game when 30 seconds have passed and everyone who managed to connect is ready
@@ -2214,6 +2221,14 @@
 		} else {
 			anyReady = true;
 		}
+	}
+
+	// Private rooms must not bypass readiness through timeout, force-start, or
+	// a participant disconnecting during the countdown. The room service owns
+	// a bounded loading deadline and cancellation.
+	if (requireAllPlayers && (!allReady || !anyReady)) {
+		readyTime = spring_notime;
+		return;
 	}
 
 	// msecs to wait until the game starts after all players are ready