diff --git a/binaries/data/mods/official/gui/test/functions_sim_entity.js b/binaries/data/mods/official/gui/test/functions_sim_entity.js
index e682e7d7f9..258b55151f 100644
--- a/binaries/data/mods/official/gui/test/functions_sim_entity.js
+++ b/binaries/data/mods/official/gui/test/functions_sim_entity.js
@@ -85,8 +85,8 @@ function worldClickHandler(event)
 				if (!selection[i].actions)
 					continue;
 				//console.write("Requesting notification for " + event.entity);
-				selection[i].requestNotification( event.entity, action, true, false );
-				selection[i].order( ORDER_GOTO, event.entity.position.x, event.entity.position.z -							selection[i].actions.escort.distance, true);
+				//selection[i].requestNotification( event.entity, action, true, false );
+				//selection[i].order( ORDER_GOTO, event.entity.position.x, event.entity.position.z -							selection[i].actions.escort.distance, true);
 			}
 		}
 		else
@@ -96,7 +96,7 @@ function worldClickHandler(event)
 				if (!selection[i].actions)
 					continue;
 				//console.write("Requesting notification for " + event.entity);		
-				selection[i].requestNotification( event.entity, action, true, false );
+				//selection[i].requestNotification( event.entity, action, true, false );
 			}
 		}	
 		
diff --git a/source/dcdt/se/Abstraction.h b/source/dcdt/se/Abstraction.h
index 2e46740a8f..543ecb4e37 100644
--- a/source/dcdt/se/Abstraction.h
+++ b/source/dcdt/se/Abstraction.h
@@ -1,157 +1,159 @@
-//Abstraction.h
-
-//DJD: definition of Abstraction class {
-
-#ifndef ABSTRACTION_H
-#define ABSTRACTION_H
-
-#include <float.h>
-#include "FunnelDeque.h"
-
-//defines an invalid entry, and "infinity", for our purposes
-#define INVALID -1
-#define INFINITY FLT_MAX
-
-//prototypes for classes defined later
-template <class T> class SeLinkFace;
-class Abstraction;
-typedef SeLinkFace<Abstraction> SeDcdtFace;
-
-//class which contains information about our topological abstraction
-class Abstraction
-{
-protected:
-	//list of adjacent nodes
-	//if this node is degree-1 in a tree, all will be NULL
-	//if it is degree-1 otherwise, one will be the root of the tree, the others will be NULL
-	//if it is degree-2 in a ring, all will be NULL
-	//if it is degree-2 otherwise, two will be degree-3 nodes on the ends of the corridor, the other will be NULL
-	//if it is degree-3, all will be degree-3 nodes on the end of the corridors
-	SeDcdtFace *m_CAdjacent[3];
-	//sum of interior angles of triangles between this one and the corresponding adjacent one
-	//INVALID if the corresponding adjacent node is NULL
-	float m_dAngle[3];
-	//width between the corresponding edge and the one counterclockwise to it, through the triangle
-	float m_dWidth[3];
-	//smallest width through the triangles between this one and the corresponding adjacent one
-	//INVALID if the corresponding adjacent node is NULL
-	float m_dChoke[3];
-	//degree of this node
-	int m_nDegree;
-	//connected component to which this triangle belongs
-	int m_nComponent;
-
-	//makes sure the index is in the range [0, 2]
-	bool CheckBounds(int n)
-	{
-		return ((n >= 0) && (n < 3));
-	}
-public:
-	//creates the abstraction with given degree
-	Abstraction(int nDegree)
-	{
-		//starts all adjacents as NULL and other information as INVALID
-		for (int i = 0; i < 3; i++)
-		{
-			m_CAdjacent[i] = NULL;
-			m_dAngle[i] = INVALID;
-			m_dWidth[i] = INVALID;
-			m_dChoke[i] = INVALID;
-		}
-		m_nDegree = nDegree;
-		m_nComponent = INVALID;
-	}
-
-	//default destructor
-	~Abstraction()
-	{
-	}
-
-	//accessor for the degree of the node
-	int Degree()
-	{
-		return m_nDegree;
-	}
-
-	//mutator for the degree of the node
-	void Degree(int nDegree)
-	{
-		m_nDegree = nDegree;
-	}
-
-	//accessor for the connected component of the node
-	int Component()
-	{
-		return m_nComponent;
-	}
-
-	//mutator for the connected component of the node
-	void Component(int nComponent)
-	{
-		m_nComponent = nComponent;
-	}
-
-	//accessor for the adjacent node with index given
-	SeDcdtFace *Adjacent(int n)
-	{
-		return (CheckBounds(n)) ? m_CAdjacent[n] : NULL;
-	}
-
-	//mutator for the adjacent node with index given
-	void Adjacent(int n, SeDcdtFace *CAdjacent)
-	{
-		if (CheckBounds(n))
-		{
-			m_CAdjacent[n] = CAdjacent;
-		}
-	}
-
-	//accessor for the angle with index given
-	float Angle(int n)
-	{
-		return (CheckBounds(n)) ? m_dAngle[n] : INVALID;
-	}
-
-	//mutator for the angle with index given
-	void Angle(int n, float dAngle)
-	{
-		if (CheckBounds(n))
-		{
-			m_dAngle[n] = dAngle;
-		}
-	}
-
-	//accessor for the width with index given
-	float Width(int n)
-	{
-		return (CheckBounds(n)) ? m_dWidth[n] : INVALID;
-	}
-
-	//mutator for the width with index given
-	void Width(int n, float dWidth)
-	{
-		if (CheckBounds(n))
-		{
-			m_dWidth[n] = dWidth;
-		}
-	}
-
-	//accessor for the choke point width with index given
-	float Choke(int n)
-	{
-		return (CheckBounds(n)) ? m_dChoke[n] : INVALID;
-	}
-
-	//mutator for the choke point width with index given
-	void Choke(int n, float dChoke)
-	{
-		if (CheckBounds(n))
-		{
-			m_dChoke[n] = dChoke;
-		}
-	}
-};
-
-#endif
-
-//definition of Abstraction class }
+//Abstraction.h
+
+//DJD: definition of Abstraction class {
+
+#ifndef ABSTRACTION_H
+#define ABSTRACTION_H
+
+#include <float.h>
+#include "FunnelDeque.h"
+
+//defines an invalid entry, and "infinity", for our purposes
+#define INVALID -1
+#ifndef INFINITY
+#define INFINITY FLT_MAX
+#endif
+
+//prototypes for classes defined later
+template <class T> class SeLinkFace;
+class Abstraction;
+typedef SeLinkFace<Abstraction> SeDcdtFace;
+
+//class which contains information about our topological abstraction
+class Abstraction
+{
+protected:
+	//list of adjacent nodes
+	//if this node is degree-1 in a tree, all will be NULL
+	//if it is degree-1 otherwise, one will be the root of the tree, the others will be NULL
+	//if it is degree-2 in a ring, all will be NULL
+	//if it is degree-2 otherwise, two will be degree-3 nodes on the ends of the corridor, the other will be NULL
+	//if it is degree-3, all will be degree-3 nodes on the end of the corridors
+	SeDcdtFace *m_CAdjacent[3];
+	//sum of interior angles of triangles between this one and the corresponding adjacent one
+	//INVALID if the corresponding adjacent node is NULL
+	float m_dAngle[3];
+	//width between the corresponding edge and the one counterclockwise to it, through the triangle
+	float m_dWidth[3];
+	//smallest width through the triangles between this one and the corresponding adjacent one
+	//INVALID if the corresponding adjacent node is NULL
+	float m_dChoke[3];
+	//degree of this node
+	int m_nDegree;
+	//connected component to which this triangle belongs
+	int m_nComponent;
+
+	//makes sure the index is in the range [0, 2]
+	bool CheckBounds(int n)
+	{
+		return ((n >= 0) && (n < 3));
+	}
+public:
+	//creates the abstraction with given degree
+	Abstraction(int nDegree)
+	{
+		//starts all adjacents as NULL and other information as INVALID
+		for (int i = 0; i < 3; i++)
+		{
+			m_CAdjacent[i] = NULL;
+			m_dAngle[i] = INVALID;
+			m_dWidth[i] = INVALID;
+			m_dChoke[i] = INVALID;
+		}
+		m_nDegree = nDegree;
+		m_nComponent = INVALID;
+	}
+
+	//default destructor
+	~Abstraction()
+	{
+	}
+
+	//accessor for the degree of the node
+	int Degree()
+	{
+		return m_nDegree;
+	}
+
+	//mutator for the degree of the node
+	void Degree(int nDegree)
+	{
+		m_nDegree = nDegree;
+	}
+
+	//accessor for the connected component of the node
+	int Component()
+	{
+		return m_nComponent;
+	}
+
+	//mutator for the connected component of the node
+	void Component(int nComponent)
+	{
+		m_nComponent = nComponent;
+	}
+
+	//accessor for the adjacent node with index given
+	SeDcdtFace *Adjacent(int n)
+	{
+		return (CheckBounds(n)) ? m_CAdjacent[n] : NULL;
+	}
+
+	//mutator for the adjacent node with index given
+	void Adjacent(int n, SeDcdtFace *CAdjacent)
+	{
+		if (CheckBounds(n))
+		{
+			m_CAdjacent[n] = CAdjacent;
+		}
+	}
+
+	//accessor for the angle with index given
+	float Angle(int n)
+	{
+		return (CheckBounds(n)) ? m_dAngle[n] : INVALID;
+	}
+
+	//mutator for the angle with index given
+	void Angle(int n, float dAngle)
+	{
+		if (CheckBounds(n))
+		{
+			m_dAngle[n] = dAngle;
+		}
+	}
+
+	//accessor for the width with index given
+	float Width(int n)
+	{
+		return (CheckBounds(n)) ? m_dWidth[n] : INVALID;
+	}
+
+	//mutator for the width with index given
+	void Width(int n, float dWidth)
+	{
+		if (CheckBounds(n))
+		{
+			m_dWidth[n] = dWidth;
+		}
+	}
+
+	//accessor for the choke point width with index given
+	float Choke(int n)
+	{
+		return (CheckBounds(n)) ? m_dChoke[n] : INVALID;
+	}
+
+	//mutator for the choke point width with index given
+	void Choke(int n, float dChoke)
+	{
+		if (CheckBounds(n))
+		{
+			m_dChoke[n] = dChoke;
+		}
+	}
+};
+
+#endif
+
+//definition of Abstraction class }
diff --git a/source/dcdt/se/FunnelDeque.h b/source/dcdt/se/FunnelDeque.h
index cac0e1ca95..c2836b7f6f 100644
--- a/source/dcdt/se/FunnelDeque.h
+++ b/source/dcdt/se/FunnelDeque.h
@@ -9,7 +9,9 @@
 #include "sr_polygon.h"
 
 //define a floating point value for pi
+#ifndef PI
 #define PI 3.1415926535897932384626433832795f
+#endif
 
 //a node in the funnel deque
 class FunnelNode
diff --git a/source/dcdt/se/Location.cpp b/source/dcdt/se/Location.cpp
index 42b0eecf36..d33900248c 100644
--- a/source/dcdt/se/Location.cpp
+++ b/source/dcdt/se/Location.cpp
@@ -152,7 +152,7 @@ float SeDcdt::RandomY()
 //returns a random number between the values given
 float SeDcdt::RandomBetween(float min, float max)
 {
-	float base = (float)rand() / (float)RAND_MAX;
+	float base = (float)rand() / (float)RAND_MAX;	// TODO: Make net-safe
 	return (base * (max - min) + min);
 }
 
diff --git a/source/network/Client.cpp b/source/network/Client.cpp
index 12cc435b5c..285e7fc49c 100644
--- a/source/network/Client.cpp
+++ b/source/network/Client.cpp
@@ -37,7 +37,8 @@ CNetClient::CNetClient(CGame *pGame, CGameAttributes *pGameAttribs):
 	m_JSI_ServerSessions(&m_ServerSessions),
 	m_pLocalPlayerSlot(NULL),
 	m_pGame(pGame),
-	m_pGameAttributes(pGameAttribs)
+	m_pGameAttributes(pGameAttribs),
+	m_TurnPending(false)
 {
 	ONCE( ScriptingInit(); );
 
@@ -51,11 +52,10 @@ CNetClient::~CNetClient()
 	g_ScriptingHost.SetGlobal("g_NetClient", JSVAL_NULL);
 	
 	SessionMap::iterator it=m_ServerSessions.begin();
-	while (it != m_ServerSessions.end())
+	for (; it != m_ServerSessions.end(); ++it)
 	{
 		delete it->second;
 	}
-	// (Isn't this an infinite loop?)
 }
 
 void CNetClient::ScriptingInit()
@@ -333,7 +333,7 @@ bool CNetClient::InGameHandler(CNetMessage *pMsg, CNetSession *pSession)
 
 	if (msgType >= NMT_COMMAND_FIRST && msgType < NMT_COMMAND_LAST)
 	{
-		pClient->QueueMessage(1, pMsg);
+		pClient->QueueIncomingMessage(pMsg);
 		TAKEN(pMsg);
 	}
 
@@ -343,17 +343,10 @@ bool CNetClient::InGameHandler(CNetMessage *pMsg, CNetSession *pSession)
 	{
 		CEndCommandBatch *msg=(CEndCommandBatch *)pMsg;
 		pClient->SetTurnLength(1, msg->m_TurnLength);
-	
-		// FIXME When the command batch has ended, we should start accepting
-		// commands for the next turn. This will be accomplished by calling
-		// NewTurn. *BUT* we shouldn't prematurely proceed game simulation
-		// since this will produce jerky playback (everything expects a sim
-		// turn to have a certain duration).
-
-		// We should make sure that any commands received after this message
-		// are queued in the next batch (#2 instead of #1). If we're already
-		// putting everything new in batch 2 - we should fast-forward a bit to
-		// catch up with the server.
+		
+		//debug_printf("Got end of batch, setting NewTurnPending\n");
+		pClient->m_TurnPending = true;
+		// We will ack the turn when our simulation calls NewTurn.
 
 		HANDLED(pMsg);
 	}
@@ -363,6 +356,13 @@ bool CNetClient::InGameHandler(CNetMessage *pMsg, CNetSession *pSession)
 	}
 }
 
+void CNetClient::QueueIncomingMessage(CNetMessage *pMsg)
+{
+	CScopeLock lock(m_Mutex);
+	debug_printf("Got a command! queueing it to 2 turns from now\n");
+	QueueMessage(2, pMsg);
+}
+
 bool CNetClient::ChatHandler(CNetMessage *pMsg, CNetSession *pSession)
 {
 	CNetClient *pClient=(CNetClient *)pSession;
@@ -437,10 +437,16 @@ int CNetClient::StartGame()
 {
 	if (m_pGame->StartGame(m_pGameAttributes) != PSRETURN_OK)
 	{
+		// TODO: Send a failed-to-launch-game message and drop out.
 		return -1;
 	}
 	else
 	{
+		debug_printf("Client StartGame - sending end-of-batch ack\n");
+		// Send an end-of-batch message for turn 0 to signal that we're ready.
+		CEndCommandBatch *pMsg=new CEndCommandBatch();
+		pMsg->m_TurnLength=1000/fps;
+		Push(pMsg);
 		return 0;
 	}
 }
@@ -450,11 +456,20 @@ CPlayer* CNetClient::GetLocalPlayer()
 	return m_pLocalPlayerSlot->GetPlayer();
 }
 
+bool CNetClient::NewTurnReady()
+{
+	return m_TurnPending;
+}
+
 void CNetClient::NewTurn()
 {
+	CScopeLock lock(m_Mutex);
+	
 	RotateBatches();
 	ClearBatch(2);
+	m_TurnPending = false;
 
+	//debug_printf("In NewTurn - sending ack\n");
 	CEndCommandBatch *pMsg=new CEndCommandBatch();
 	pMsg->m_TurnLength=1000/fps;
 	Push(pMsg);
@@ -463,5 +478,6 @@ void CNetClient::NewTurn()
 void CNetClient::QueueLocalCommand(CNetMessage *pMsg)
 {
 	// Don't save these locally, since they'll be bounced by the server anyway
+	//debug_printf("Sending command from client\n");
 	Push(pMsg);
 }
diff --git a/source/network/Client.h b/source/network/Client.h
index 1d1f6678d5..b00ca70017 100644
--- a/source/network/Client.h
+++ b/source/network/Client.h
@@ -1,12 +1,13 @@
 #ifndef INCLUDED_NETWORK_CLIENT
 #define INCLUDED_NETWORK_CLIENT
 
-#include "ps/CStr.h"
 #include "Session.h"
 
 #include "simulation/TurnManager.h"
 #include "simulation/ScriptObject.h"
 #include "scripting/ScriptableObject.h"
+#include "ps/CStr.h"
+#include "ps/ThreadUtil.h"
 #include "ps/scripting/JSMap.h"
 
 #include <map>
@@ -51,12 +52,22 @@ class CNetClient: public CNetSession, protected CTurnManager, public CJSObject<C
 	void OnClientConnect(int sessionID, const CStrW& name);
 	void OnClientDisconnect(int sessionID);
 	void OnStartGameMessage();
+	void QueueIncomingMessage(CNetMessage *pMsg);
 
 	// JS Interface Functions
 	bool JSI_BeginConnect(JSContext *cx, uintN argc, jsval *argv);
 	static void ScriptingInit();
+	
+	// Are we currently in a locally-yet-unsimulated turn?
+	// This is set to true when we receive a command batch and cleared in NewTurn().
+	// The server also ensures that it does not send a new turn until we ack one.
+	bool m_TurnPending;
+	
+	// Mutex for accessing batches
+	CMutex m_Mutex;
 
 protected:
+	virtual bool NewTurnReady();
 	virtual void NewTurn();
 	virtual void QueueLocalCommand(CNetMessage *pMsg);
 
diff --git a/source/network/Server.cpp b/source/network/Server.cpp
index 96d7cd1178..261753462a 100644
--- a/source/network/Server.cpp
+++ b/source/network/Server.cpp
@@ -1,7 +1,5 @@
 #include "precompiled.h"
 
-#include <algorithm>
-
 #include "Server.h"
 #include "ServerSession.h"
 #include "Network.h"
@@ -14,6 +12,7 @@
 #include "ps/Player.h"
 #include "ps/CLogger.h"
 #include "ps/CConsole.h"
+#include "ps/ThreadUtil.h"
 
 #define LOG_CAT_NET "net"
 
@@ -346,8 +345,6 @@ void CNetServer::Broadcast(CNetMessage *pMsg)
 
 int CNetServer::StartGame()
 {
-	Broadcast(new CStartGame());
-	
 	if (m_pGame->StartGame(m_pGameAttributes) != PSRETURN_OK)
 	{
 		return -1;
@@ -370,8 +367,11 @@ int CNetServer::StartGame()
 			++it;
 		}
 		
+		debug_printf("Server StartGame\n");
+		Broadcast(new CStartGame());	
+		
 		// This is the signal for everyone to start their simulations.
-		SendBatch(1);
+		//SendBatch(1);
 
 		return 0;
 	}
@@ -382,26 +382,51 @@ void CNetServer::GetDefaultListenAddress(CSocketAddress &address)
 	address=CSocketAddress(PS_DEFAULT_PORT, IPv4);
 }
 
+bool CNetServer::NewTurnReady()
+{
+	// Wait for all clients to check in
+	SessionMap::iterator it = m_Sessions.begin();
+	for (; it != m_Sessions.end(); ++it)
+	{
+		if (!it->second->IsReadyForTurn())
+			return false;
+	}
+	return true;
+}
+
 void CNetServer::NewTurn()
 {
+	CScopeLock lock(m_Mutex);
+	
+	// Clear ready flags on clients
+	SessionMap::iterator it = m_Sessions.begin();
+	for (; it != m_Sessions.end(); ++it)
+	{
+		it->second->SetReadyForTurn(false);
+	}
+	
 	RecordBatch(2);
 
 	RotateBatches();
 	ClearBatch(2);
 
 	IterateBatch(1, CSimulation::GetMessageMask, m_pGame->GetSimulation());
+	//debug_printf("In NewTurn - sending batch\n");
 	SendBatch(1);
 	//IterateBatch(1, SendToObservers, this);
 }
 
 void CNetServer::QueueLocalCommand(CNetMessage *pMsg)
 {
+	//debug_printf("Queueing command from server\n");
 	QueueIncomingCommand(pMsg);
 }
 
 void CNetServer::QueueIncomingCommand(CNetMessage *pMsg)
 {
+	CScopeLock lock(m_Mutex);
 	LOG(NORMAL, LOG_CAT_NET, "CNetServer::QueueIncomingCommand(): %s.", pMsg->GetString().c_str());
+	debug_printf("Got a command! queueing it to 2 turns from now\n");
 	QueueMessage(2, pMsg);
 }
 
diff --git a/source/network/Server.h b/source/network/Server.h
index 5f25504b01..0615159e18 100644
--- a/source/network/Server.h
+++ b/source/network/Server.h
@@ -81,6 +81,9 @@ private:
 	// JS Interface Methods
 	bool JSI_Open(JSContext *cx, uintN argc, jsval *argv);
 	static void ScriptingInit();
+	
+	// Synchronization object for batches
+	CMutex m_Mutex;
 
 protected:
 	friend class CNetServerSession;
@@ -108,6 +111,7 @@ protected:
 	virtual void OnAccept(const CSocketAddress &);
 
 	// OVERRIDES FROM CTurnManager
+	virtual bool NewTurnReady();
 	virtual void NewTurn();
 	virtual void QueueLocalCommand(CNetMessage *pMsg);
 
diff --git a/source/network/ServerSession.cpp b/source/network/ServerSession.cpp
index 9f6bf3a4b1..5c70f65f1d 100644
--- a/source/network/ServerSession.cpp
+++ b/source/network/ServerSession.cpp
@@ -12,7 +12,8 @@ CNetServerSession::CNetServerSession(CNetServer *pServer, CSocketInternal *pInt,
 	m_pPlayer(NULL),
 	m_pPlayerSlot(NULL),
 	m_IsObserver(false),
-	m_ID(-1)
+	m_ID(-1),
+	m_ReadyForTurn(false)
 {
 	ONCE(
 		ScriptingInit();
@@ -193,7 +194,7 @@ bool CNetServerSession::InGameHandler(CNetMessage *pMsg, CNetSession *pNetSessio
 	switch (pMsg->GetType())
 	{
 	case NMT_EndCommandBatch:
-		// TODO Update client timing information and recalculate turn length
+		pSession->m_ReadyForTurn = true;
 		HANDLED(pMsg);
 
 	default:
diff --git a/source/network/ServerSession.h b/source/network/ServerSession.h
index 36e56d792f..1241b0d192 100644
--- a/source/network/ServerSession.h
+++ b/source/network/ServerSession.h
@@ -22,6 +22,7 @@ class CNetServerSession: public CNetSession, public CJSObject<CNetServerSession>
 	CPlayerSlot *m_pPlayerSlot;
 	bool m_IsObserver;
 	int m_ID;
+	bool m_ReadyForTurn;	// Is the last turn acknowledged?
 	
 	// JS INTERFACE
 	static void ScriptingInit();
@@ -51,6 +52,10 @@ public:
 	{	return m_pPlayerSlot; }
 	inline int GetID()
 	{	return m_ID; }
+	inline bool IsReadyForTurn()
+	{	return m_ReadyForTurn; }
+	inline void SetReadyForTurn(bool value)
+	{	m_ReadyForTurn = value; }
 
 	// Called by server when starting the game, after sending NMT_StartGame to
 	// all connected clients.
diff --git a/source/ps/GameSetup/GameSetup.cpp b/source/ps/GameSetup/GameSetup.cpp
index 56baa9c86a..39bd88091c 100644
--- a/source/ps/GameSetup/GameSetup.cpp
+++ b/source/ps/GameSetup/GameSetup.cpp
@@ -900,7 +900,7 @@ void EarlyInit()
 	timer_Init();
 
 	// Initialise the low-quality rand function
-	srand(time(NULL));
+	srand(time(NULL));	// NOTE: this rand should *not* be used for simulation!
 }
 
 void Init(const CmdLineArgs& args, uint flags)
diff --git a/source/renderer/ModelRenderer.cpp b/source/renderer/ModelRenderer.cpp
index 51c9cd362f..224ddfbd90 100644
--- a/source/renderer/ModelRenderer.cpp
+++ b/source/renderer/ModelRenderer.cpp
@@ -388,7 +388,7 @@ void BatchModelRenderer::EndFrame()
 		if (mdeftracker->m_Slots > mostslots)
 		{
 			mostslots = mdeftracker->m_Slots;
-			debug_printf("BatchModelRenderer: SubmissionSlots maximum: %u\n", mostslots);
+			//debug_printf("BatchModelRenderer: SubmissionSlots maximum: %u\n", mostslots);
 		}
 		mdeftracker->m_Slots = 0;
 	}
diff --git a/source/simulation/Entity.cpp b/source/simulation/Entity.cpp
index d18c52f4f0..9ce6ed9857 100644
--- a/source/simulation/Entity.cpp
+++ b/source/simulation/Entity.cpp
@@ -473,6 +473,11 @@ void CEntity::UpdateOrders( size_t timestep )
 	while( !m_orderQueue.empty() )
 	{
 		CEntityOrder* current = &m_orderQueue.front();
+		CStr name = me;
+#ifdef DEBUG_SYNCHRONIZATION
+		debug_printf("Order for %ls: %d (src %d)\n", 
+			m_base->m_Tag.c_str(), current->m_type, current->m_source);
+#endif
 
 		if( current->m_type != m_lastState )
 		{
@@ -877,6 +882,7 @@ void CEntity::DispatchFormationEvent( int type )
 }
 void CEntity::Repath()
 {
+	debug_printf("Repath\n");
 	CVector2D destination;
 	CEntityOrder::EOrderSource orderSource = CEntityOrder::SOURCE_PLAYER;
 
diff --git a/source/simulation/EntityOrders.h b/source/simulation/EntityOrders.h
index 32b17a6419..7bf4114c87 100644
--- a/source/simulation/EntityOrders.h
+++ b/source/simulation/EntityOrders.h
@@ -82,22 +82,22 @@ class CEntityOrder
 public:
 	enum EOrderType
 	{
-		ORDER_INVALID,
-		ORDER_GOTO_NOPATHING,
-		ORDER_GOTO_SMOOTHED,
-		ORDER_GOTO_COLLISION,
-		ORDER_GOTO_WAYPOINT,
-		ORDER_GOTO_WAYPOINT_CONTACT,
-		ORDER_GOTO,
-		ORDER_RUN,
-		ORDER_PATROL,
-		ORDER_PATH_END_MARKER,
-		ORDER_GENERIC,
-		ORDER_GENERIC_NOPATHING,
-		ORDER_PRODUCE,
-		ORDER_START_CONSTRUCTION,
-		ORDER_NOTIFY_REQUEST,
-		ORDER_LAST
+		ORDER_INVALID,				// 0
+		ORDER_GOTO_NOPATHING,		// 1
+		ORDER_GOTO_SMOOTHED,		// 2
+		ORDER_GOTO_COLLISION,		// 3
+		ORDER_GOTO_WAYPOINT,		// 4
+		ORDER_GOTO_WAYPOINT_CONTACT,// 5
+		ORDER_GOTO,					// 6
+		ORDER_RUN,					// 7
+		ORDER_PATROL,				// 8
+		ORDER_PATH_END_MARKER,		// 9
+		ORDER_GENERIC,				// 10
+		ORDER_GENERIC_NOPATHING,	// 11
+		ORDER_PRODUCE,				// 12
+		ORDER_START_CONSTRUCTION,	// 13
+		ORDER_NOTIFY_REQUEST,		// 14
+		ORDER_LAST					// 15
 	};
 	EOrderType m_type;
 
diff --git a/source/simulation/EntityScriptInterface.cpp b/source/simulation/EntityScriptInterface.cpp
index 7728f24cfa..8c6d9f78e2 100644
--- a/source/simulation/EntityScriptInterface.cpp
+++ b/source/simulation/EntityScriptInterface.cpp
@@ -30,6 +30,7 @@
 #include "ProductionQueue.h"
 #include "TechnologyCollection.h"
 #include "TerritoryManager.h"
+#include "Simulation.h"
 #include "Stance.h"
 
 #include <algorithm>
@@ -134,7 +135,7 @@ JSBool CEntity::Construct( JSContext* cx, JSObject* UNUSED(obj), uint argc, jsva
 	debug_assert( argc >= 2 );
 
 	CVector3D position;
-	float orientation = (float)( PI * ( (double)( rand() & 0x7fff ) / (double)0x4000 ) );
+	float orientation = g_Game->GetSimulation()->RandFloat() * 2 * PI;
 
 	JSObject* jsEntityTemplate = JSVAL_TO_OBJECT( argv[0] );
 	CStrW templateName;
@@ -398,7 +399,7 @@ jsval_t CEntity::GetSpawnPoint( JSContext* UNUSED(cx), uintN argc, jsval* argv )
 
 		// Pick a start point
 
-		int edge = rand() & 3;
+		int edge = g_Game->GetSimulation()->RandInt( 4 );
 		int point;
 
 		double max_w = oabb->m_w + spawn_clearance + 1.0;
@@ -411,12 +412,12 @@ jsval_t CEntity::GetSpawnPoint( JSContext* UNUSED(cx), uintN argc, jsval* argv )
 		CVector2D pos( m_position );
 		if( edge & 1 )
 		{
-			point = rand() % ( 2 * d_count ) - d_count;
+			point = g_Game->GetSimulation()->RandInt( 2 * d_count ) - d_count;
 			pos += ( oabb->m_v * (float)max_w + d_step * (float)point ) * ( ( edge & 2 ) ? -1.0f : 1.0f );
 		}
 		else
 		{
-			point = rand() % ( 2 * w_count ) - w_count;
+			point = g_Game->GetSimulation()->RandInt( 2 * w_count ) - w_count;
 			pos += ( oabb->m_u * (float)max_d + w_step * (float)point ) * ( ( edge & 2 ) ? -1.0f : 1.0f );
 		}
 
@@ -478,8 +479,7 @@ jsval_t CEntity::GetSpawnPoint( JSContext* UNUSED(cx), uintN argc, jsval* argv )
 	else if( m_bounds->m_type == CBoundingObject::BOUND_CIRCLE )
 	{
 		float ang;
-		ang = (float)( rand() & 0x7fff ) / (float)0x4000; /* 0...2 */
-		ang *= PI;
+		ang = g_Game->GetSimulation()->RandFloat() * 2 * PI;
 		float radius = m_bounds->m_radius + 1.0f + spawn_clearance;
 		float d_ang = spawn_clearance / ( 2.0f * radius );
 		float ang_end = ang + 2.0f * PI;
diff --git a/source/simulation/Simulation.cpp b/source/simulation/Simulation.cpp
index 587c10d474..cecfbce690 100644
--- a/source/simulation/Simulation.cpp
+++ b/source/simulation/Simulation.cpp
@@ -83,20 +83,30 @@ bool CSimulation::Update(double frameTime)
 	if (m_DeltaTime >= 0.0)
 	{
 		// A new simulation frame is required.
-
-		PROFILE( "simulation turn" );
-		Simulate();
-		double turnLength = m_pTurnManager->GetTurnLength() / 1000.0;
-		m_DeltaTime -= turnLength;
-		if (m_DeltaTime >= 0.0)
+		if (m_pTurnManager->NewTurnReady())
 		{
-			// The desired sim frame rate can't be achieved - we're being called
-			// with average(frameTime) > turnLength.
-			// Let the caller know we can't go fast enough - they should try
-			// cutting down on Interpolate and rendering, and call us a few times
-			// with frameTime == 0 to give us a chance to catch up.
-			ok = false;
-			debug_printf("WARNING: missing a simulation turn due to low FPS");
+			PROFILE( "simulation turn" );
+			Simulate();
+			double turnLength = m_pTurnManager->GetTurnLength() / 1000.0;
+			m_DeltaTime -= turnLength;
+			if (m_DeltaTime >= 0.0)
+			{
+				// The desired sim frame rate can't be achieved - we're being called
+				// with average(frameTime) > turnLength.
+				// Let the caller know we can't go fast enough - they should try
+				// cutting down on Interpolate and rendering, and call us a few times
+				// with frameTime == 0 to give us a chance to catch up.
+				ok = false;
+				debug_printf("WARNING: missing a simulation turn due to low FPS\n");
+			}
+		}
+		else
+		{
+			// The network is lagging behind the simulation rate. 
+			// Set delta time back to zero so we don't jump into the middle
+			// of the next simulation frame when we get the next turn.
+			// This creates "lag" on the client rather than just jumpiness.
+			m_DeltaTime = 0;
 		}
 	}
 
@@ -141,7 +151,9 @@ void CSimulation::Simulate()
 	uint time = m_pTurnManager->GetTurnLength();
 	
 	m_Time += time / 1000.0f;
-	//debug_printf("Simulation turn: %.3lf\n", m_Time);
+#ifdef DEBUG_SYNCHRONIZATION
+	debug_printf("Simulation turn: %.3lf\n", m_Time);
+#endif
 
 	PROFILE_START( "scheduler tick" );
 	g_Scheduler.Update(time);
@@ -167,6 +179,10 @@ void CSimulation::Simulate()
 	m_pTurnManager->NewTurn();
 	m_pTurnManager->IterateBatch(0, TranslateMessage, this);
 	PROFILE_END( "turn manager update" );
+	
+#ifdef DEBUG_SYNCHRONIZATION
+	debug_printf("End turn\n", m_Time);
+#endif
 }
 
 // Location randomizer, for group orders...
diff --git a/source/simulation/TurnManager.h b/source/simulation/TurnManager.h
index 62a6bc6467..8f9b15d3a9 100644
--- a/source/simulation/TurnManager.h
+++ b/source/simulation/TurnManager.h
@@ -100,10 +100,14 @@ public:
 	// CSimulation will use this to determine when to perform the deterministic
 	// update and call NewTurn()
 	uint GetTurnLength();
-
+	
 	// Called by CSimulation when the current turn time has passed.
 	virtual void NewTurn()=0;
+	
+	// Used by CSimulation to ask whether it can call NewTurn.
+	virtual bool NewTurnReady() { return true; }
 
+	// Apply a function to all messages in a given batch.
 	void IterateBatch(uint batch, BatchIteratorFunc *func, void *userdata);
 
 	// Queue a command originating from the local player.