diff --git a/src/am_map.cpp b/src/am_map.cpp
index ec6381754..627d6ea1e 100644
--- a/src/am_map.cpp
+++ b/src/am_map.cpp
@@ -261,7 +261,7 @@ CCMD(togglemap)
 {
 	if (gameaction == ga_nothing)
 	{
-		gameaction = ga_togglemap;
+		AM_ToggleMap();
 	}
 }
 
diff --git a/src/common/objects/dobject.cpp b/src/common/objects/dobject.cpp
index e124a975c..5b2658a70 100644
--- a/src/common/objects/dobject.cpp
+++ b/src/common/objects/dobject.cpp
@@ -573,6 +573,7 @@ void DObject::Serialize(FSerializer &arc)
 	SerializeFlag("justspawned", OF_JustSpawned);
 	SerializeFlag("spawned", OF_Spawned);
 	SerializeFlag("networked", OF_Networked);
+	SerializeFlag("clientside", OF_ClientSide);
 		
 	ObjectFlags |= OF_SerialSuccess;
 
@@ -668,7 +669,7 @@ void NetworkEntityManager::SetClientNetworkEntity(DObject* mo, const unsigned in
 
 void NetworkEntityManager::AddNetworkEntity(DObject* const ent)
 {
-	if (ent->IsNetworked())
+	if (ent->IsNetworked() || ent->IsClientside())
 		return;
 
 	// Slot 0 is reserved for the world.
@@ -758,6 +759,18 @@ DEFINE_ACTION_FUNCTION_NATIVE(DObject, GetNetworkID, GetNetworkID)
 	ACTION_RETURN_INT(self->GetNetworkID());
 }
 
+static int IsClientside(DObject* self)
+{
+	return self->IsClientside();
+}
+
+DEFINE_ACTION_FUNCTION_NATIVE(DObject, IsClientside, IsClientside)
+{
+	PARAM_SELF_PROLOGUE(DObject);
+
+	ACTION_RETURN_BOOL(self->IsClientside());
+}
+
 static void EnableNetworking(DObject* const self, const bool enable)
 {
 	self->EnableNetworking(enable);
diff --git a/src/common/objects/dobject.h b/src/common/objects/dobject.h
index c0b6aecb5..9925cb88e 100644
--- a/src/common/objects/dobject.h
+++ b/src/common/objects/dobject.h
@@ -359,6 +359,7 @@ private:
 public:
 	inline bool IsNetworked() const { return (ObjectFlags & OF_Networked); }
 	inline uint32_t GetNetworkID() const { return _networkID; }
+	inline bool IsClientside() const { return (ObjectFlags & OF_ClientSide); }
 	void SetNetworkID(const uint32_t id);
 	void ClearNetworkID();
 	void RemoveFromNetwork();
diff --git a/src/common/objects/dobjgc.h b/src/common/objects/dobjgc.h
index f5514255d..39f0011e0 100644
--- a/src/common/objects/dobjgc.h
+++ b/src/common/objects/dobjgc.h
@@ -27,6 +27,7 @@ enum EObjectFlags
 	OF_Spawned			= 1 << 12,      // Thinker was spawned at all (some thinkers get deleted before spawning)
 	OF_Released			= 1 << 13,		// Object was released from the GC system and should not be processed by GC function
 	OF_Networked		= 1 << 14,		// Object has a unique network identifier that makes it synchronizable between all clients.
+	OF_ClientSide		= 1 << 15,		// Object is owned by a specific client rather than the server
 };
 
 template<class T> class TObjPtr;
diff --git a/src/common/objects/dobjtype.cpp b/src/common/objects/dobjtype.cpp
index eac10469a..a7c3dfb0f 100644
--- a/src/common/objects/dobjtype.cpp
+++ b/src/common/objects/dobjtype.cpp
@@ -440,7 +440,7 @@ DObject *PClass::CreateNew()
 	ConstructNative (mem);
 
 	if (Defaults != nullptr)
-		((DObject *)mem)->ObjectFlags |= ((DObject *)Defaults)->ObjectFlags & OF_Transient;
+		((DObject *)mem)->ObjectFlags |= ((DObject *)Defaults)->ObjectFlags & (OF_Transient | OF_ClientSide);
 
 	((DObject *)mem)->SetClass (const_cast<PClass *>(this));
 	InitializeSpecials(mem, Defaults, &PClass::SpecialInits);
diff --git a/src/d_net.cpp b/src/d_net.cpp
index b14869a33..d3251fce1 100644
--- a/src/d_net.cpp
+++ b/src/d_net.cpp
@@ -73,6 +73,8 @@
 #include "i_interface.h"
 #include "savegamemanager.h"
 
+void P_RunClientsideLogic();
+
 EXTERN_CVAR (Int, disableautosave)
 EXTERN_CVAR (Int, autosavecount)
 EXTERN_CVAR (Bool, cl_capfps)
@@ -1800,6 +1802,12 @@ static bool ShouldStabilizeTick()
 void TryRunTics()
 {
 	GC::CheckGC();
+
+	if (ToggleFullscreen)
+	{
+		ToggleFullscreen = false;
+		AddCommandString("toggle vid_fullscreen");
+	}
 	
 	bool doWait = (cl_capfps || pauseext || (!netgame && r_NoInterpolate && !M_IsAnimated()));
 	if (vid_dontdowait && (vid_maxfps > 0 || vid_vsync))
@@ -1852,14 +1860,6 @@ void TryRunTics()
 	// commands to predict.
 	if (runTics <= 0)
 	{
-		// If we actually did have some tics available, make sure the UI
-		// still has a chance to run.
-		for (int i = 0; i < totalTics; ++i)
-		{
-			C_Ticker();
-			M_Ticker();
-		}
-
 		// If we're in between a tic, try and balance things out.
 		if (totalTics <= 0)
 			TicStabilityWait();
@@ -1875,6 +1875,11 @@ void TryRunTics()
 			S_UpdateSounds(players[consoleplayer].camera);	// Update sounds only after predicting the client's newest position.
 		}
 
+		// If we actually did have some tics available, make sure the UI
+		// still has a chance to run.
+		for (int i = 0; i < totalTics; ++i)
+			P_RunClientsideLogic();
+
 		return;
 	}
 
@@ -1895,8 +1900,6 @@ void TryRunTics()
 		if (advancedemo)
 			D_DoAdvanceDemo();
 
-		C_Ticker();
-		M_Ticker();
 		G_Ticker();
 		MakeConsistencies();
 		++gametic;
@@ -1912,6 +1915,11 @@ void TryRunTics()
 	}
 	P_PredictPlayer(&players[consoleplayer]);
 	S_UpdateSounds(players[consoleplayer].camera);	// Update sounds only after predicting the client's newest position.
+
+	// These should use the actual tics since they're not actually tied to the gameplay logic.
+	// Make sure it always comes after so the HUD has the correct game state when updating.
+	for (int i = 0; i < totalTics; ++i)
+		P_RunClientsideLogic();
 }
 
 void Net_NewClientTic()
diff --git a/src/g_game.cpp b/src/g_game.cpp
index 88fc30144..30274dd93 100644
--- a/src/g_game.cpp
+++ b/src/g_game.cpp
@@ -1136,12 +1136,6 @@ void G_Ticker ()
 			primaryLevel->DoReborn(i, false);
 	}
 
-	if (ToggleFullscreen)
-	{
-		ToggleFullscreen = false;
-		AddCommandString ("toggle vid_fullscreen");
-	}
-
 	// do things to change the game state
 	oldgamestate = gamestate;
 	while (gameaction != ga_nothing)
@@ -1192,19 +1186,10 @@ void G_Ticker ()
 		case ga_worlddone:
 			G_DoWorldDone ();
 			break;
-		case ga_screenshot:
-			M_ScreenShot (shotfile.GetChars());
-			shotfile = "";
-			gameaction = ga_nothing;
-			break;
 		case ga_fullconsole:
 			G_FullConsole ();
 			gameaction = ga_nothing;
 			break;
-		case ga_togglemap:
-			AM_ToggleMap ();
-			gameaction = ga_nothing;
-			break;
 		case ga_resumeconversation:
 			P_ResumeConversation ();
 			gameaction = ga_nothing;
@@ -1263,18 +1248,12 @@ void G_Ticker ()
 		}
 	}
 
-	// [ZZ] also tick the UI part of the events
-	primaryLevel->localEventManager->UiTick();
 	C_RunDelayedCommands();
 
 	// do main actions
 	switch (gamestate)
 	{
 	case GS_LEVEL:
-		P_Ticker ();
-		primaryLevel->automap->Ticker ();
-		break;
-
 	case GS_TITLELEVEL:
 		P_Ticker ();
 		break;
@@ -1303,9 +1282,6 @@ void G_Ticker ()
 	default:
 		break;
 	}
-
-	// [MK] Additional ticker for UI events right after all others
-	primaryLevel->localEventManager->PostUiTick();
 }
 
 
@@ -1844,7 +1820,8 @@ void G_ScreenShot (const char *filename)
 	if (gameaction == ga_nothing)
 	{
 		shotfile = filename;
-		gameaction = ga_screenshot;
+		M_ScreenShot(shotfile.GetChars());
+		shotfile = "";
 	}
 }
 
diff --git a/src/g_level.cpp b/src/g_level.cpp
index f39588cae..97a17a554 100644
--- a/src/g_level.cpp
+++ b/src/g_level.cpp
@@ -457,7 +457,7 @@ void G_NewInit ()
 	int i;
 
 	// Destory all old player refrences that may still exist
-	TThinkerIterator<AActor> it(primaryLevel, NAME_PlayerPawn, STAT_TRAVELLING);
+	TThinkerIterator<AActor> it(primaryLevel, NAME_PlayerPawn, STAT_TRAVELLING, false);
 	AActor *pawn, *next;
 
 	next = it.Next();
@@ -473,6 +473,7 @@ void G_NewInit ()
 	// Destroy thinkers that may remain after change level failure
 	// Usually, the list contains just a sentinel when such error occurred
 	primaryLevel->Thinkers.DestroyThinkersInList(STAT_TRAVELLING);
+	primaryLevel->ClientsideThinkers.DestroyThinkersInList(STAT_TRAVELLING); // This isn't currently supported, but maybe in the future
 
 	G_ClearSnapshots ();
 	netgame = false;
@@ -586,6 +587,7 @@ void G_InitNew (const char *mapname, bool bTitleLevel)
 	for (auto Level : AllLevels())
 	{
 		Level->Thinkers.DestroyThinkersInList(STAT_STATIC);
+		Level->ClientsideThinkers.DestroyThinkersInList(STAT_STATIC);
 	}
 
 	if (paused)
@@ -1780,6 +1782,7 @@ int FLevelLocals::FinishTravel ()
 	// Since this list is excluded from regular thinker cleaning, anything that may survive through here
 	// will endlessly multiply and severely break the following savegames or just simply crash on broken pointers.
 	Thinkers.DestroyThinkersInList(STAT_TRAVELLING);
+	ClientsideThinkers.DestroyThinkersInList(STAT_TRAVELLING);
 	return failnum;
 }
  
@@ -2284,6 +2287,7 @@ void FLevelLocals::Mark()
 	GC::Mark(SpotState);
 	GC::Mark(FraggleScriptThinker);
 	GC::Mark(ACSThinker);
+	GC::Mark(ClientSideACSThinker);
 	GC::Mark(automap);
 	GC::Mark(interpolator.Head);
 	GC::Mark(SequenceListHead);
@@ -2296,6 +2300,7 @@ void FLevelLocals::Mark()
 		GC::Mark(localEventManager->LastEventHandler);
 	}
 	Thinkers.MarkRoots();
+	ClientsideThinkers.MarkRoots();
 	canvasTextureInfo.Mark();
 	for (auto &c : CorpseQueue)
 	{
diff --git a/src/g_levellocals.h b/src/g_levellocals.h
index da3bc58c2..2bb55f332 100644
--- a/src/g_levellocals.h
+++ b/src/g_levellocals.h
@@ -138,8 +138,8 @@ struct FLevelLocals
 	void ClearAllSubsectorLinks();
 	void TranslateLineDef (line_t *ld, maplinedef_t *mld, int lineindexforid = -1);
 	int TranslateSectorSpecial(int special);
-	bool IsTIDUsed(int tid);
-	int FindUniqueTID(int start_tid, int limit);
+	bool IsTIDUsed(int tid, bool clientside);
+	int FindUniqueTID(int start_tid, int limit, bool clientside);
 	int GetConversation(int conv_id);
 	int GetConversation(FName classname);
 	void SetConversation(int convid, PClassActor *Class, int dlgindex);
@@ -249,6 +249,7 @@ public:
 	void SpawnExtraPlayers();
 	void Serialize(FSerializer &arc, bool hubload);
 	DThinker *FirstThinker (int statnum);
+	DThinker* FirstClientsideThinker(int statnum);
 
 	// g_Game
 	void PlayerReborn (int player);
@@ -295,12 +296,21 @@ public:
 	}
 	template<class T> TThinkerIterator<T> GetThinkerIterator(FName subtype = NAME_None, int statnum = MAX_STATNUM+1)
 	{
-		if (subtype == NAME_None) return TThinkerIterator<T>(this, statnum);
-		else return TThinkerIterator<T>(this, subtype, statnum);
+		if (subtype == NAME_None) return TThinkerIterator<T>(this, statnum, false);
+		else return TThinkerIterator<T>(this, subtype, statnum, false);
 	}
 	template<class T> TThinkerIterator<T> GetThinkerIterator(FName subtype, int statnum, AActor *prev)
 	{
-		return TThinkerIterator<T>(this, subtype, statnum, prev);
+		return TThinkerIterator<T>(this, subtype, statnum, prev, false);
+	}
+	template<class T> TThinkerIterator<T> GetClientsideThinkerIterator(FName subtype = NAME_None, int statnum = MAX_STATNUM + 1)
+	{
+		if (subtype == NAME_None) return TThinkerIterator<T>(this, statnum, true);
+		else return TThinkerIterator<T>(this, subtype, statnum, true);
+	}
+	template<class T> TThinkerIterator<T> GetClientsideThinkerIterator(FName subtype, int statnum, AActor* prev)
+	{
+		return TThinkerIterator<T>(this, subtype, statnum, prev, true);
 	}
 	FActorIterator GetActorIterator(int tid)
 	{
@@ -314,6 +324,18 @@ public:
 	{
 		return NActorIterator(TIDHash, type, tid);
 	}
+	FActorIterator GetClientSideActorIterator(int tid)
+	{
+		return FActorIterator(ClientSideTIDHash, tid);
+	}
+	FActorIterator GetClientSideActorIterator(int tid, AActor* start)
+	{
+		return FActorIterator(ClientSideTIDHash, tid, start);
+	}
+	NActorIterator GetClientSideActorIterator(FName type, int tid)
+	{
+		return NActorIterator(ClientSideTIDHash, type, tid);
+	}
 	AActor *SingleActorFromTID(int tid, AActor *defactor)
 	{
 		return tid == 0 ? defactor : GetActorIterator(tid).Next();
@@ -411,6 +433,7 @@ public:
 	void ClearTIDHashes ()
 	{
 		memset(TIDHash, 0, sizeof(TIDHash));
+		memset(ClientSideTIDHash, 0, sizeof(ClientSideTIDHash));
 	}
 
 
@@ -441,6 +464,24 @@ public:
 		thinker->Construct(std::forward<Args>(args)...);
 		return thinker;
 	}
+
+	DThinker* CreateClientsideThinker(PClass* cls, int statnum = STAT_DEFAULT)
+	{
+		DThinker* thinker = static_cast<DThinker*>(cls->CreateNew());
+		assert(thinker->IsKindOf(RUNTIME_CLASS(DThinker)));
+		thinker->ObjectFlags |= OF_JustSpawned | OF_ClientSide | OF_Transient;
+		ClientsideThinkers.Link(thinker, statnum);
+		thinker->Level = this;
+		return thinker;
+	}
+
+	template<typename T, typename... Args>
+	T* CreateClientsideThinker(Args&&... args)
+	{
+		auto thinker = static_cast<T*>(CreateClientsideThinker(RUNTIME_CLASS(T), T::DEFAULT_STAT));
+		thinker->Construct(std::forward<Args>(args)...);
+		return thinker;
+	}
 	
 	void SetMusic();
 
@@ -511,6 +552,7 @@ public:
 
 	FBehaviorContainer Behaviors;
 	AActor *TIDHash[128];
+	AActor* ClientSideTIDHash[128];
 
 	TArray<FStrifeDialogueNode *> StrifeDialogues;
 	FDialogueIDMap DialogueRoots;
@@ -674,6 +716,7 @@ public:
 	TArray<particle_t>	Particles;
 	TArray<uint16_t>	ParticlesInSubsec;
 	FThinkerCollection Thinkers;
+	FThinkerCollection ClientsideThinkers;
 
 	TArray<DVector2>	Scrolls;		// NULL if no DScrollers in this level
 
@@ -710,6 +753,7 @@ public:
 	TArray<TObjPtr<AActor *>> CorpseQueue;
 	TObjPtr<DFraggleThinker *> FraggleScriptThinker = MakeObjPtr<DFraggleThinker*>(nullptr);
 	TObjPtr<DACSThinker*> ACSThinker = MakeObjPtr<DACSThinker*>(nullptr);
+	TObjPtr<DACSThinker*> ClientSideACSThinker = MakeObjPtr<DACSThinker*>(nullptr);
 
 	TObjPtr<DSpotState *> SpotState = MakeObjPtr<DSpotState*>(nullptr);
 
diff --git a/src/gamedata/info.cpp b/src/gamedata/info.cpp
index 3fc5d2e76..1cd624e22 100644
--- a/src/gamedata/info.cpp
+++ b/src/gamedata/info.cpp
@@ -63,6 +63,7 @@ extern void ClearStrifeTypes();
 
 TArray<PClassActor *> PClassActor::AllActorClasses;
 FRandom FState::pr_statetics("StateTics");
+FCRandom FState::pr_csstatetics("ClientsideStateTics");
 
 cycle_t ActionCycles;
 
@@ -489,7 +490,7 @@ void PClassActor::InitializeDefaults()
 				memset(Defaults + ParentClass->Size, 0, Size - ParentClass->Size);
 			}
 
-			optr->ObjectFlags = ((DObject*)ParentClass->Defaults)->ObjectFlags & OF_Transient;
+			optr->ObjectFlags = ((DObject*)ParentClass->Defaults)->ObjectFlags & (OF_Transient | OF_ClientSide);
 		}
 		else
 		{
diff --git a/src/gamedata/info.h b/src/gamedata/info.h
index 69ad560e0..8d2f20c19 100644
--- a/src/gamedata/info.h
+++ b/src/gamedata/info.h
@@ -150,6 +150,14 @@ public:
 		}
 		return Tics + pr_statetics.GenRand32() % (TicRange + 1);
 	}
+	inline int GetClientsideTics() const
+	{
+		if (TicRange == 0)
+		{
+			return Tics;
+		}
+		return Tics + pr_csstatetics.GenRand32() % (TicRange + 1);
+	}
 	inline int GetMisc1() const
 	{
 		return Misc1;
@@ -176,6 +184,7 @@ public:
 	static PClassActor *StaticFindStateOwner (const FState *state, PClassActor *info);
 	static FString StaticGetStateName(const FState *state, PClassActor *info = nullptr);
 	static FRandom pr_statetics;
+	static FCRandom pr_csstatetics;
 
 };
 
diff --git a/src/p_saveg.cpp b/src/p_saveg.cpp
index d759add72..659e67664 100644
--- a/src/p_saveg.cpp
+++ b/src/p_saveg.cpp
@@ -949,6 +949,7 @@ void FLevelLocals::Serialize(FSerializer &arc, bool hubload)
 	if (arc.isReading())
 	{
 		Thinkers.DestroyAllThinkers();
+		ClientsideThinkers.DestroyAllThinkers();
 		interpolator.ClearInterpolations();
 		arc.ReadObjects(hubload);
 		// If there have been object deserialization errors we must absolutely not continue here because scripted objects can do unpredictable things.
diff --git a/src/p_setup.cpp b/src/p_setup.cpp
index 85b592bb3..c18cb1621 100644
--- a/src/p_setup.cpp
+++ b/src/p_setup.cpp
@@ -296,6 +296,7 @@ void FLevelLocals::ClearLevelData(bool fullgc)
 	
 	interpolator.ClearInterpolations();	// [RH] Nothing to interpolate on a fresh level.
 	Thinkers.DestroyAllThinkers(fullgc);
+	ClientsideThinkers.DestroyAllThinkers(fullgc);
 	ClearAllSubsectorLinks(); // can't be done as part of the polyobj deletion process.
 
 	total_monsters = total_items = total_secrets =
@@ -331,6 +332,7 @@ void FLevelLocals::ClearLevelData(bool fullgc)
 	if (SpotState) SpotState->Destroy();
 	SpotState = nullptr;
 	ACSThinker = nullptr;
+	ClientSideACSThinker = nullptr;
 	FraggleScriptThinker = nullptr;
 	CorpseQueue.Clear();
 	canvasTextureInfo.EmptyList();
@@ -644,6 +646,7 @@ void P_Shutdown ()
 	for (auto Level : AllLevels())
 	{
 		Level->Thinkers.DestroyThinkersInList(STAT_STATIC);
+		Level->ClientsideThinkers.DestroyThinkersInList(STAT_STATIC);
 	}
 	P_FreeLevelData ();
 	// [ZZ] delete global event handlers
diff --git a/src/p_tick.cpp b/src/p_tick.cpp
index efe35f412..1837fb3da 100644
--- a/src/p_tick.cpp
+++ b/src/p_tick.cpp
@@ -38,11 +38,61 @@
 #include "events.h"
 #include "actorinlines.h"
 #include "g_game.h"
+#include "am_map.h"
 #include "i_interface.h"
 
 extern gamestate_t wipegamestate;
 extern uint8_t globalfreeze, globalchangefreeze;
 
+void C_Ticker();
+void M_Ticker();
+
+//==========================================================================
+//
+// P_RunClientsideLogic
+//
+// Handles all logic that should be ran every tick including while
+// predicting. Only put non-playsim behaviors in here to avoid desyncs
+// when playing online.
+//
+//==========================================================================
+
+void P_RunClientsideLogic()
+{
+	C_Ticker();
+	M_Ticker();
+
+	// [ZZ] also tick the UI part of the events
+	primaryLevel->localEventManager->UiTick();
+
+	if (gamestate == GS_LEVEL || gamestate == GS_TITLELEVEL)
+	{
+		for (auto level : AllLevels())
+		{
+			auto it = level->GetClientsideThinkerIterator<AActor>();
+			AActor* ac = nullptr;
+			while ((ac = it.Next()) != nullptr)
+			{
+				ac->ClearInterpolation();
+				ac->ClearFOVInterpolation();
+			}
+
+			P_ThinkParticles(level);	// [RH] make the particles think
+
+			level->ClientsideThinkers.RunClientsideThinkers(level);
+		}
+
+		StatusBar->CallTick();
+
+		// TODO: Should this be called on all maps...?
+		if (gamestate == GS_LEVEL)
+			primaryLevel->automap->Ticker();
+	}
+
+	// [MK] Additional ticker for UI events right after all others
+	primaryLevel->localEventManager->PostUiTick();
+}
+
 //==========================================================================
 //
 // P_CheckTickerPaused
@@ -196,8 +246,6 @@ void P_Ticker (void)
 			ac->ClearFOVInterpolation();
 		}
 
-		P_ThinkParticles(Level);	// [RH] make the particles think
-
 		for (i = 0; i < MAXPLAYERS; i++)
 			if (Level->PlayerInGame(i))
 				P_PlayerThink(Level->Players[i]);
@@ -222,5 +270,4 @@ void P_Ticker (void)
 		if (players[consoleplayer].mo->Vel.Length() > primaryLevel->max_velocity) { primaryLevel->max_velocity = players[consoleplayer].mo->Vel.Length(); }
 		primaryLevel->avg_velocity += (players[consoleplayer].mo->Vel.Length() - primaryLevel->avg_velocity) / primaryLevel->maptime;
 	}
-	StatusBar->CallTick();		// Status bar should tick AFTER the thinkers to properly reflect the level's state at this time.
 }
diff --git a/src/playsim/dthinker.cpp b/src/playsim/dthinker.cpp
index 51cf3a670..05e5e56c3 100644
--- a/src/playsim/dthinker.cpp
+++ b/src/playsim/dthinker.cpp
@@ -267,6 +267,66 @@ void FThinkerCollection::RunThinkers(FLevelLocals *Level)
 	ThinkCycles.Unclock();
 }
 
+//==========================================================================
+//
+// This version doesn't modify the level since that's already been done by
+// the networked ticking. This also runs while the player is predicting
+// to make sure it keeps ticking regardless of network game status.
+//
+//==========================================================================
+
+void FThinkerCollection::RunClientsideThinkers(FLevelLocals* Level)
+{
+	int i, count;
+
+	bool dolights;
+	if ((gl_lights && vid_rendermode == 4) || (r_dynlights && vid_rendermode != 4))
+	{
+		dolights = true;// Level->lights || (Level->flags3 & LEVEL3_LIGHTCREATED);
+	}
+	else
+	{
+		dolights = false;
+	}
+
+	auto recreateLights = [=]() {
+		auto it = Level->GetClientsideThinkerIterator<AActor>();
+
+		// Set dynamic lights at the end of the tick, so that this catches all changes being made through the last frame.
+		while (auto ac = it.Next())
+		{
+			if (ac->flags8 & MF8_RECREATELIGHTS)
+			{
+				ac->flags8 &= ~MF8_RECREATELIGHTS;
+				if (dolights) ac->SetDynamicLights();
+			}
+			// This was merged from P_RunEffects to eliminate the costly duplicate ThinkerIterator loop.
+			if ((ac->effects || ac->fountaincolor) && ac->ShouldRenderLocally() && !Level->isFrozen())
+			{
+				P_RunEffect(ac, ac->effects);
+			}
+		}
+	};
+
+	// Tick every thinker left from last time
+	for (i = STAT_FIRST_THINKING; i <= MAX_STATNUM; ++i)
+	{
+		Thinkers[i].TickThinkers(nullptr);
+	}
+
+	// Keep ticking the fresh thinkers until there are no new ones.
+	do
+	{
+		count = 0;
+		for (i = STAT_FIRST_THINKING; i <= MAX_STATNUM; ++i)
+		{
+			count += FreshThinkers[i].TickThinkers(&Thinkers[i]);
+		}
+	} while (count != 0);
+
+	recreateLights();
+}
+
 //==========================================================================
 //
 // Destroy every thinker
@@ -784,6 +844,11 @@ DThinker *FLevelLocals::FirstThinker (int statnum)
 	return Thinkers.FirstThinker(statnum);
 }
 
+DThinker* FLevelLocals::FirstClientsideThinker(int statnum)
+{
+	return ClientsideThinkers.FirstThinker(statnum);
+}
+
 //==========================================================================
 //
 //
@@ -797,7 +862,10 @@ void DThinker::ChangeStatNum (int statnum)
 		statnum = MAX_STATNUM;
 	}
 	Remove();
-	Level->Thinkers.Link(this, statnum);
+	if (IsClientside())
+		Level->ClientsideThinkers.Link(this, statnum);
+	else
+		Level->Thinkers.Link(this, statnum);
 }
 
 static void ChangeStatNum(DThinker *thinker, int statnum)
@@ -923,8 +991,9 @@ size_t DThinker::PropagateMark()
 //
 //==========================================================================
 
-FThinkerIterator::FThinkerIterator (FLevelLocals *l, const PClass *type, int statnum) : Level(l)
+FThinkerIterator::FThinkerIterator (FLevelLocals *l, const PClass *type, int statnum, bool clientside) : Level(l)
 {
+	m_ThinkerPool = clientside ? &Level->ClientsideThinkers : &Level->Thinkers;
 	if ((unsigned)statnum > MAX_STATNUM)
 	{
 		m_Stat = STAT_FIRST_THINKING;
@@ -945,8 +1014,9 @@ FThinkerIterator::FThinkerIterator (FLevelLocals *l, const PClass *type, int sta
 //
 //==========================================================================
 
-FThinkerIterator::FThinkerIterator (FLevelLocals *l, const PClass *type, int statnum, DThinker *prev) : Level(l)
+FThinkerIterator::FThinkerIterator (FLevelLocals *l, const PClass *type, int statnum, DThinker *prev, bool clientside) : Level(l)
 {
+	m_ThinkerPool = clientside ? &Level->ClientsideThinkers : &Level->Thinkers;
 	if ((unsigned)statnum > MAX_STATNUM)
 	{
 		m_Stat = STAT_FIRST_THINKING;
@@ -977,7 +1047,7 @@ FThinkerIterator::FThinkerIterator (FLevelLocals *l, const PClass *type, int sta
 
 void FThinkerIterator::Reinit ()
 {
-	m_CurrThinker = Level->Thinkers.Thinkers[m_Stat].GetHead();
+	m_CurrThinker = m_ThinkerPool->Thinkers[m_Stat].GetHead();
 	m_SearchingFresh = false;
 }
 
@@ -1018,7 +1088,7 @@ DThinker *FThinkerIterator::Next (bool exact)
 			}
 			if ((m_SearchingFresh = !m_SearchingFresh))
 			{
-				m_CurrThinker = Level->Thinkers.FreshThinkers[m_Stat].GetHead();
+				m_CurrThinker = m_ThinkerPool->FreshThinkers[m_Stat].GetHead();
 			}
 		} while (m_SearchingFresh);
 		if (m_SearchStats)
@@ -1029,7 +1099,7 @@ DThinker *FThinkerIterator::Next (bool exact)
 				m_Stat = STAT_FIRST_THINKING;
 			}
 		}
-		m_CurrThinker = Level->Thinkers.Thinkers[m_Stat].GetHead();
+		m_CurrThinker = m_ThinkerPool->Thinkers[m_Stat].GetHead();
 		m_SearchingFresh = false;
 	} while (m_SearchStats && m_Stat != STAT_FIRST_THINKING);
 	return nullptr;
diff --git a/src/playsim/dthinker.h b/src/playsim/dthinker.h
index 78dcd1520..ab4a453b8 100644
--- a/src/playsim/dthinker.h
+++ b/src/playsim/dthinker.h
@@ -79,6 +79,7 @@ struct FThinkerCollection
 	}
 
 	void RunThinkers(FLevelLocals *Level);	// The level is needed to tick the lights
+	void RunClientsideThinkers(FLevelLocals* Level);
 	void DestroyAllThinkers(bool fullgc = true);
 	void SerializeThinkers(FSerializer &arc, bool keepPlayers);
 	void MarkRoots();
@@ -132,14 +133,15 @@ protected:
 	const PClass *m_ParentType;
 private:
 	FLevelLocals *Level;
+	FThinkerCollection* m_ThinkerPool;
 	DThinker *m_CurrThinker;
 	uint8_t m_Stat;
 	bool m_SearchStats;
 	bool m_SearchingFresh;
 
 public:
-	FThinkerIterator (FLevelLocals *Level, const PClass *type, int statnum=MAX_STATNUM+1);
-	FThinkerIterator (FLevelLocals *Level, const PClass *type, int statnum, DThinker *prev);
+	FThinkerIterator (FLevelLocals *Level, const PClass *type, int statnum=MAX_STATNUM+1, bool clientside = false);
+	FThinkerIterator (FLevelLocals *Level, const PClass *type, int statnum, DThinker *prev, bool clientside = false);
 	DThinker *Next (bool exact = false);
 	void Reinit ();
 };
@@ -147,19 +149,19 @@ public:
 template <class T> class TThinkerIterator : public FThinkerIterator
 {
 public:
-	TThinkerIterator (FLevelLocals *Level, int statnum=MAX_STATNUM+1) : FThinkerIterator (Level, RUNTIME_CLASS(T), statnum)
+	TThinkerIterator (FLevelLocals *Level, int statnum=MAX_STATNUM+1, bool clientside = false) : FThinkerIterator (Level, RUNTIME_CLASS(T), statnum, clientside)
 	{
 	}
-	TThinkerIterator (FLevelLocals *Level, int statnum, DThinker *prev) : FThinkerIterator (Level, RUNTIME_CLASS(T), statnum, prev)
+	TThinkerIterator (FLevelLocals *Level, int statnum, DThinker *prev, bool clientside = false) : FThinkerIterator (Level, RUNTIME_CLASS(T), statnum, prev, clientside)
 	{
 	}
-	TThinkerIterator (FLevelLocals *Level, const PClass *subclass, int statnum=MAX_STATNUM+1) : FThinkerIterator(Level, subclass, statnum)
+	TThinkerIterator (FLevelLocals *Level, const PClass *subclass, int statnum=MAX_STATNUM+1, bool clientside = false) : FThinkerIterator(Level, subclass, statnum, clientside)
 	{
 	}
-	TThinkerIterator (FLevelLocals *Level, FName subclass, int statnum=MAX_STATNUM+1) : FThinkerIterator(Level, PClass::FindClass(subclass), statnum)
+	TThinkerIterator (FLevelLocals *Level, FName subclass, int statnum=MAX_STATNUM+1, bool clientside = false) : FThinkerIterator(Level, PClass::FindClass(subclass), statnum, clientside)
 	{
 	}
-	TThinkerIterator (FLevelLocals *Level, FName subclass, int statnum, DThinker *prev) : FThinkerIterator(Level, PClass::FindClass(subclass), statnum, prev)
+	TThinkerIterator (FLevelLocals *Level, FName subclass, int statnum, DThinker *prev, bool clientside = false) : FThinkerIterator(Level, PClass::FindClass(subclass), statnum, prev, clientside)
 	{
 	}
 	T *Next (bool exact = false)
diff --git a/src/playsim/p_acs.cpp b/src/playsim/p_acs.cpp
index 34b78219a..6fac4c79c 100644
--- a/src/playsim/p_acs.cpp
+++ b/src/playsim/p_acs.cpp
@@ -653,6 +653,11 @@ struct CallReturn
 };
 
 
+static bool IsClientSideScript(const ScriptPtr& script)
+{
+	return (script.Flags & SCRIPTF_ClientSide);
+}
+
 class DLevelScript : public DObject
 {
 	DECLARE_CLASS(DLevelScript, DObject)
@@ -675,7 +680,7 @@ public:
 	};
 
 	DLevelScript(FLevelLocals *l, AActor *who, line_t *where, int num, const ScriptPtr *code, FBehavior *module,
-		const int *args, int argcount, int flags);
+		const int *args, int argcount, int flags, bool clientside);
 
 	void Serialize(FSerializer &arc);
 	int RunScript();
@@ -700,6 +705,7 @@ public:
 
 protected:
 	DLevelScript	*next, *prev;
+	TObjPtr<DACSThinker*> controller;
 	int				script;
 	TArray<int32_t>	Localvars;
 	int				*pc;
@@ -783,7 +789,7 @@ private:
 };
 
 static DLevelScript *P_GetScriptGoing (FLevelLocals *Level, AActor *who, line_t *where, int num, const ScriptPtr *code, FBehavior *module,
-	const int *args, int argcount, int flags);
+	const int *args, int argcount, int flags, bool clientside);
 
 
 struct FBehavior::ArrayInfo
@@ -2015,6 +2021,13 @@ void FBehaviorContainer::MarkLevelVarStrings()
 			script->MarkLocalVarStrings();
 		}
 	}
+	if (Level->ClientSideACSThinker != nullptr)
+	{
+		for (DLevelScript* script = Level->ClientSideACSThinker->Scripts; script != NULL; script = script->GetNext())
+		{
+			script->MarkLocalVarStrings();
+		}
+	}
 }
 
 void FBehaviorContainer::LockLevelVarStrings(int levelnum)
@@ -2032,6 +2045,13 @@ void FBehaviorContainer::LockLevelVarStrings(int levelnum)
 			script->LockLocalVarStrings(levelnum);
 		}
 	}
+	if (Level->ClientSideACSThinker != nullptr)
+	{
+		for (DLevelScript* script = Level->ClientSideACSThinker->Scripts; script != NULL; script = script->GetNext())
+		{
+			script->LockLocalVarStrings(levelnum);
+		}
+	}
 }
 
 void FBehaviorContainer::UnlockLevelVarStrings(int levelnum)
@@ -3307,7 +3327,7 @@ void FBehavior::StartTypedScripts (uint16_t type, AActor *activator, bool always
 		if (ptr->Type == type)
 		{
 			DLevelScript *runningScript = P_GetScriptGoing (Level, activator, NULL, ptr->Number,
-				ptr, this, &arg1, 1, always ? ACS_ALWAYS : 0);
+				ptr, this, &arg1, 1, always ? ACS_ALWAYS : 0, IsClientSideScript(*ptr));
 			if (nullptr != runningScript && runNow)
 			{
 				runningScript->RunScript();
@@ -3330,6 +3350,12 @@ void FBehaviorContainer::StopMyScripts (AActor *actor)
 	{
 		controller->StopScriptsFor (actor);
 	}
+
+	controller = actor->Level->ClientSideACSThinker;
+	if (controller != NULL)
+	{
+		controller->StopScriptsFor(actor);
+	}
 }
 
 
@@ -3510,8 +3536,6 @@ void DLevelScript::Serialize(FSerializer &arc)
 
 void DLevelScript::Unlink ()
 {
-	DACSThinker *controller = Level->ACSThinker;
-
 	if (controller->LastScript == this)
 	{
 		controller->LastScript = prev;
@@ -3536,8 +3560,6 @@ void DLevelScript::Unlink ()
 
 void DLevelScript::Link ()
 {
-	DACSThinker *controller = Level->ACSThinker;
-
 	next = controller->Scripts;
 	GC::WriteBarrier(this, next);
 	if (controller->Scripts)
@@ -3556,8 +3578,6 @@ void DLevelScript::Link ()
 
 void DLevelScript::PutLast ()
 {
-	DACSThinker *controller = Level->ACSThinker;
-
 	if (controller->LastScript == this)
 		return;
 
@@ -3578,8 +3598,6 @@ void DLevelScript::PutLast ()
 
 void DLevelScript::PutFirst ()
 {
-	DACSThinker *controller = Level->ACSThinker;
-
 	if (controller->Scripts == this)
 		return;
 
@@ -5856,11 +5874,11 @@ int DLevelScript::CallFunction(int argCount, int funcIndex, int32_t *args, int &
 			break;
 
 		case ACSF_UniqueTID:
-			return Level->FindUniqueTID(argCount > 0 ? args[0] : 0, (argCount > 1 && args[1] >= 0) ? args[1] : 0);
+			return Level->FindUniqueTID(argCount > 0 ? args[0] : 0, (argCount > 1 && args[1] >= 0) ? args[1] : 0, false);
 
 		case ACSF_IsTIDUsed:
 			MIN_ARG_COUNT(1);
-			return Level->IsTIDUsed(args[0]);
+			return Level->IsTIDUsed(args[0], false);
 
 		case ACSF_Sqrt:
 			MIN_ARG_COUNT(1);
@@ -6902,7 +6920,6 @@ PClass *DLevelScript::GetClassForIndex(int index) const
 
 int DLevelScript::RunScript()
 {
-	DACSThinker *controller = Level->ACSThinker;
 	ACSLocalVariables locals(Localvars);
 	ACSLocalArrays noarrays;
 	ACSLocalArrays *localarrays = &noarrays;
@@ -10389,9 +10406,9 @@ scriptwait:
 #undef PushtoStack
 
 static DLevelScript *P_GetScriptGoing (FLevelLocals *l, AActor *who, line_t *where, int num, const ScriptPtr *code, FBehavior *module,
-	const int *args, int argcount, int flags)
+	const int *args, int argcount, int flags, bool clientside)
 {
-	DACSThinker *controller = l->ACSThinker;
+	DACSThinker *controller = clientside ? l->ClientSideACSThinker : l->ACSThinker;
 	DLevelScript **running;
 
 	if (controller && !(flags & ACS_ALWAYS) && (running = controller->RunningScripts.CheckKey(num)) != NULL)
@@ -10404,16 +10421,28 @@ static DLevelScript *P_GetScriptGoing (FLevelLocals *l, AActor *who, line_t *whe
 		return NULL;
 	}
 
-	return Create<DLevelScript> (l, who, where, num, code, module, args, argcount, flags);
+	return Create<DLevelScript> (l, who, where, num, code, module, args, argcount, flags, clientside);
 }
 
 DLevelScript::DLevelScript (FLevelLocals *l, AActor *who, line_t *where, int num, const ScriptPtr *code, FBehavior *module,
-	const int *args, int argcount, int flags)
+	const int *args, int argcount, int flags, bool clientside)
 	: activeBehavior (module)
 {
 	Level = l;
-	if (Level->ACSThinker == nullptr)
-		Level->ACSThinker = Level->CreateThinker<DACSThinker>();
+	if (clientside)
+	{
+		if (Level->ClientSideACSThinker == nullptr)
+			Level->ClientSideACSThinker = Level->CreateClientsideThinker<DACSThinker>();
+
+		controller = Level->ClientSideACSThinker;
+	}
+	else
+	{
+		if (Level->ACSThinker == nullptr)
+			Level->ACSThinker = Level->CreateThinker<DACSThinker>();
+
+		controller = Level->ACSThinker;
+	}
 
 	script = num;
 	assert(code->VarCount >= code->ArgCount);
@@ -10440,11 +10469,11 @@ DLevelScript::DLevelScript (FLevelLocals *l, AActor *who, line_t *where, int num
 	// goes by while they're in their default state.
 
 	if (!(flags & ACS_ALWAYS))
-		Level->ACSThinker->RunningScripts[num] = this;
+		controller->RunningScripts[num] = this;
 
 	Link();
 
-	if (Level->flags2 & LEVEL2_HEXENHACK)
+	if (!clientside && (Level->flags2 & LEVEL2_HEXENHACK))
 	{
 		PutLast();
 	}
@@ -10452,14 +10481,20 @@ DLevelScript::DLevelScript (FLevelLocals *l, AActor *who, line_t *where, int num
 	DPrintf(DMSG_SPAMMY, "%s started.\n", ScriptPresentation(num).GetChars());
 }
 
-void SetScriptState (DACSThinker *controller, int script, DLevelScript::EScriptState state)
+void SetScriptState (FLevelLocals& level, int script, DLevelScript::EScriptState state)
 {
 	DLevelScript **running;
 
+	auto controller = level.ACSThinker;
 	if (controller != NULL && (running = controller->RunningScripts.CheckKey(script)) != NULL)
 	{
 		(*running)->SetState (state);
+		return;
 	}
+
+	controller = level.ClientSideACSThinker;
+	if (controller != NULL && (running = controller->RunningScripts.CheckKey(script)) != NULL)
+		(*running)->SetState(state);
 }
 
 void FLevelLocals::DoDeferedScripts ()
@@ -10471,33 +10506,32 @@ void FLevelLocals::DoDeferedScripts ()
 	for(int i = info->deferred.Size()-1; i>=0; i--)
 	{
 		acsdefered_t *def = &info->deferred[i];
+		scriptdata = Behaviors.FindScript(def->script, module);
+		if (scriptdata == nullptr)
+		{
+			Printf("P_DoDeferredScripts: Unknown %s\n", ScriptPresentation(def->script).GetChars());
+			continue;
+		}
+
 		switch (def->type)
 		{
 		case acsdefered_t::defexecute:
 		case acsdefered_t::defexealways:
-			scriptdata = Behaviors.FindScript (def->script, module);
-			if (scriptdata)
-			{
-				P_GetScriptGoing (this, (unsigned)def->playernum < MAXPLAYERS &&
-					PlayerInGame(def->playernum) ? Players[def->playernum]->mo : nullptr,
-					nullptr, def->script,
-					scriptdata, module,
-					def->args, 3,
-					def->type == acsdefered_t::defexealways ? ACS_ALWAYS : 0);
-			}
-			else
-			{
-				Printf ("P_DoDeferredScripts: Unknown %s\n", ScriptPresentation(def->script).GetChars());
-			}
+			P_GetScriptGoing (this, (unsigned)def->playernum < MAXPLAYERS &&
+				PlayerInGame(def->playernum) ? Players[def->playernum]->mo : nullptr,
+				nullptr, def->script,
+				scriptdata, module,
+				def->args, 3,
+				def->type == acsdefered_t::defexealways ? ACS_ALWAYS : 0, IsClientSideScript(*scriptdata));
 			break;
 
 		case acsdefered_t::defsuspend:
-			SetScriptState (ACSThinker, def->script, DLevelScript::SCRIPT_Suspended);
+			SetScriptState (*this, def->script, DLevelScript::SCRIPT_Suspended);
 			DPrintf (DMSG_SPAMMY, "Deferred suspend of %s\n", ScriptPresentation(def->script).GetChars());
 			break;
 
 		case acsdefered_t::defterminate:
-			SetScriptState (ACSThinker, def->script, DLevelScript::SCRIPT_PleaseRemove);
+			SetScriptState (*this, def->script, DLevelScript::SCRIPT_PleaseRemove);
 			DPrintf (DMSG_SPAMMY, "Deferred terminate of %s\n", ScriptPresentation(def->script).GetChars());
 			break;
 		}
@@ -10561,8 +10595,15 @@ int P_StartScript (FLevelLocals *Level, AActor *who, line_t *where, int script,
 					return false;
 				}
 			}
-			DLevelScript *runningScript = P_GetScriptGoing (Level, who, where, script,
-				scriptdata, module, args, argcount, flags);
+
+			DLevelScript* runningScript = nullptr;
+			const bool clientside = IsClientSideScript(*scriptdata);
+			if (!(flags & ACS_NET) || !clientside || (who && Level->isConsolePlayer(who->player->mo)))
+			{
+				runningScript = P_GetScriptGoing(Level, who, where, script,
+					scriptdata, module, args, argcount, flags, clientside);
+			}
+
 			if (runningScript != NULL)
 			{
 				if (flags & ACS_WANTRESULT)
@@ -10596,7 +10637,7 @@ void P_SuspendScript (FLevelLocals *Level, int script, const char *map)
 	if (strnicmp (Level->MapName.GetChars(), map, 8))
 		addDefered (FindLevelInfo (map), acsdefered_t::defsuspend, script, NULL, 0, NULL);
 	else
-		SetScriptState (Level->ACSThinker, script, DLevelScript::SCRIPT_Suspended);
+		SetScriptState (*Level, script, DLevelScript::SCRIPT_Suspended);
 }
 
 void P_TerminateScript (FLevelLocals *Level, int script, const char *map)
@@ -10604,7 +10645,7 @@ void P_TerminateScript (FLevelLocals *Level, int script, const char *map)
 	if (strnicmp (Level->MapName.GetChars(), map, 8))
 		addDefered (FindLevelInfo (map), acsdefered_t::defterminate, script, NULL, 0, NULL);
 	else
-		SetScriptState (Level->ACSThinker, script, DLevelScript::SCRIPT_PleaseRemove);
+		SetScriptState (*Level, script, DLevelScript::SCRIPT_PleaseRemove);
 }
 
 FSerializer &Serialize(FSerializer &arc, const char *key, acsdefered_t &defer, acsdefered_t *def)
diff --git a/src/playsim/p_acs.h b/src/playsim/p_acs.h
index 695b22948..0ac9f139b 100644
--- a/src/playsim/p_acs.h
+++ b/src/playsim/p_acs.h
@@ -339,7 +339,8 @@ enum
 // Script flags
 enum
 {
-	SCRIPTF_Net = 0x0001	// Safe to "puke" in multiplayer
+	SCRIPTF_Net = 0x0001,		 // Safe to "puke" in multiplayer
+	SCRIPTF_ClientSide = 0x0002, // Executed locally for clients but not across them
 };
 
 enum ACSFormat { ACS_Old, ACS_Enhanced, ACS_LittleEnhanced, ACS_Unknown };
diff --git a/src/playsim/p_maputl.cpp b/src/playsim/p_maputl.cpp
index 8c172c479..7379ff743 100644
--- a/src/playsim/p_maputl.cpp
+++ b/src/playsim/p_maputl.cpp
@@ -294,38 +294,36 @@ void AActor::UnlinkFromWorld (FLinkContext *ctx)
 		// killough 8/11/98: simpler scheme using pointers-to-pointers for prev
 		// pointers, allows head node pointers to be treated like everything else
 		AActor **prev = sprev;
-		AActor  *next = snext;
-
-		if (prev != NULL)	// prev will be NULL if this actor gets deleted due to cleaning up from a broken savegame
+		if (prev != NULL)
 		{
+			AActor* next = snext;
 			if ((*prev = next))  // unlink from sector list
 				next->sprev = prev;
 			snext = NULL;
 			sprev = (AActor **)(size_t)0xBeefCafe;	// Woo! Bug-catching value!
-
-			// phares 3/14/98
-			//
-			// Save the sector list pointed to by touching_sectorlist.
-			// In P_SetThingPosition, we'll keep any nodes that represent
-			// sectors the Thing still touches. We'll add new ones then, and
-			// delete any nodes for sectors the Thing has vacated. Then we'll
-			// put it back into touching_sectorlist. It's done this way to
-			// avoid a lot of deleting/creating for nodes, when most of the
-			// time you just get back what you deleted anyway.
-
-			if (ctx != nullptr)
-			{
-				ctx->sector_list = touching_sectorlist;
-				ctx->render_list = touching_rendersectors;
-			}
-			else
-			{
-				P_DelSeclist(touching_sectorlist, &sector_t::touching_thinglist);
-				P_DelSeclist(touching_rendersectors, &sector_t::touching_renderthings);
-			}
-			touching_sectorlist = nullptr; //to be restored by P_SetThingPosition
-			touching_rendersectors = nullptr;
 		}
+
+		// phares 3/14/98
+		//
+		// Save the sector list pointed to by touching_sectorlist.
+		// In P_SetThingPosition, we'll keep any nodes that represent
+		// sectors the Thing still touches. We'll add new ones then, and
+		// delete any nodes for sectors the Thing has vacated. Then we'll
+		// put it back into touching_sectorlist. It's done this way to
+		// avoid a lot of deleting/creating for nodes, when most of the
+		// time you just get back what you deleted anyway.
+		if (ctx != nullptr)
+		{
+			ctx->sector_list = touching_sectorlist;
+			ctx->render_list = touching_rendersectors;
+		}
+		else
+		{
+			P_DelSeclist(touching_sectorlist, &sector_t::touching_thinglist);
+			P_DelSeclist(touching_rendersectors, &sector_t::touching_renderthings);
+		}
+		touching_sectorlist = nullptr; //to be restored by P_SetThingPosition
+		touching_rendersectors = nullptr;
 	}
 		
 	if (!(flags & MF_NOBLOCKMAP))
@@ -469,32 +467,37 @@ void AActor::LinkToWorld(FLinkContext *ctx, bool spawningmapthing, sector_t *sec
 	subsector = Level->PointInRenderSubsector(Pos());	// this is from the rendering nodes, not the gameplay nodes!
 	section = subsector->section;
 
+	const bool clientside = IsClientside();
 	if (!(flags & MF_NOSECTOR))
 	{
-		// invisible things don't go into the sector links
-		// killough 8/11/98: simpler scheme using pointer-to-pointer prev
-		// pointers, allows head nodes to be treated like everything else
+		if (!clientside)
+		{
+			// invisible things don't go into the sector links
+			// killough 8/11/98: simpler scheme using pointer-to-pointer prev
+			// pointers, allows head nodes to be treated like everything else
 
-		AActor **link = &sector->thinglist;
-		AActor *next = *link;
-		if ((snext = next))
-			next->sprev = &snext;
-		sprev = link;
-		*link = this;
+			AActor** link = &sector->thinglist;
+			AActor* next = *link;
+			if ((snext = next))
+				next->sprev = &snext;
+			sprev = link;
+			*link = this;
 
-		// phares 3/16/98
-		//
-		// If sector_list isn't NULL, it has a collection of sector
-		// nodes that were just removed from this Thing.
+			// phares 3/16/98
+			//
+			// If sector_list isn't NULL, it has a collection of sector
+			// nodes that were just removed from this Thing.
 
-		// Collect the sectors the object will live in by looking at
-		// the existing sector_list and adding new nodes and deleting
-		// obsolete ones.
+			// Collect the sectors the object will live in by looking at
+			// the existing sector_list and adding new nodes and deleting
+			// obsolete ones.
+
+			// When a node is deleted, its sector links (the links starting
+			// at sector_t->touching_thinglist) are broken. When a node is
+			// added, new sector links are created.
+			touching_sectorlist = P_CreateSecNodeList(this, radius, ctx != nullptr ? ctx->sector_list : nullptr, &sector_t::touching_thinglist);	// Attach to thing
+		}
 
-		// When a node is deleted, its sector links (the links starting
-		// at sector_t->touching_thinglist) are broken. When a node is
-		// added, new sector links are created.
-		touching_sectorlist = P_CreateSecNodeList(this, radius, ctx != nullptr? ctx->sector_list : nullptr, &sector_t::touching_thinglist);	// Attach to thing
 		if (renderradius >= 0) touching_rendersectors = P_CreateSecNodeList(this, RenderRadius(), ctx != nullptr ? ctx->render_list : nullptr, &sector_t::touching_renderthings);
 		else
 		{
@@ -505,7 +508,7 @@ void AActor::LinkToWorld(FLinkContext *ctx, bool spawningmapthing, sector_t *sec
 
 
 	// link into blockmap (inert things don't need to be in the blockmap)
-	if (!(flags & MF_NOBLOCKMAP))
+	if (!(flags & MF_NOBLOCKMAP) && !clientside)
 	{
 		FPortalGroupArray check;
 
diff --git a/src/playsim/p_mobj.cpp b/src/playsim/p_mobj.cpp
index 216d13db7..8dc686f71 100644
--- a/src/playsim/p_mobj.cpp
+++ b/src/playsim/p_mobj.cpp
@@ -143,6 +143,7 @@ static FRandom pr_uniquetid("UniqueTID");
 // PUBLIC DATA DEFINITIONS -------------------------------------------------
 
 FRandom pr_spawnmobj ("SpawnActor");
+FCRandom pr_spawncsmobj("SpawnClientsideActor");
 FRandom pr_bounce("Bounce");
 FRandom pr_spawnmissile("SpawnMissile");
 
@@ -196,9 +197,9 @@ DEFINE_FIELD(DBehavior, Level)
 
 void AActor::EnableNetworking(const bool enable)
 {
-	if (!enable)
+	if (!enable && !IsClientside())
 	{
-		ThrowAbortException(X_OTHER, "Cannot disable networking on Actors. Consider a Thinker instead.");
+		ThrowAbortException(X_OTHER, "Cannot disable networking on Actors. Consider a Thinker or clientside Actor instead.");
 		return;
 	}
 
@@ -844,7 +845,7 @@ bool AActor::IsMapActor()
 
 inline int GetTics(AActor* actor, FState * newstate)
 {
-	int tics = newstate->GetTics();
+	int tics = actor->IsClientside() ? newstate->GetClientsideTics() : newstate->GetTics();
 	if (actor->isFast() && newstate->GetFast())
 	{
 		return tics - (tics>>1);
@@ -3484,7 +3485,7 @@ void AActor::AddToHash ()
 	else
 	{
 		int hash = TIDHASH (tid);
-		auto &slot = Level->TIDHash[hash];
+		auto &slot = IsClientside() ? Level->ClientSideTIDHash[hash] : Level->TIDHash[hash];
 
 		inext = slot;
 		iprev = &slot;
@@ -3542,9 +3543,9 @@ void AActor::SetTID (int newTID)
 //
 //==========================================================================
 
-bool FLevelLocals::IsTIDUsed(int tid)
+bool FLevelLocals::IsTIDUsed(int tid, bool clientside)
 {
-	AActor *probe = TIDHash[tid & 127];
+	AActor *probe = clientside ? ClientSideTIDHash[tid & 127] : TIDHash[tid & 127];
 	while (probe != NULL)
 	{
 		if (probe->tid == tid)
@@ -3567,7 +3568,7 @@ bool FLevelLocals::IsTIDUsed(int tid)
 //
 //==========================================================================
 
-int FLevelLocals::FindUniqueTID(int start_tid, int limit)
+int FLevelLocals::FindUniqueTID(int start_tid, int limit, bool clientside)
 {
 	int tid;
 
@@ -3583,7 +3584,7 @@ int FLevelLocals::FindUniqueTID(int start_tid, int limit)
 		}
 		for (tid = start_tid; tid <= limit; ++tid)
 		{
-			if (tid != 0 && !IsTIDUsed(tid))
+			if (tid != 0 && !IsTIDUsed(tid, clientside))
 			{
 				return tid;
 			}
@@ -3605,7 +3606,7 @@ int FLevelLocals::FindUniqueTID(int start_tid, int limit)
 	{
 		// Use a positive starting TID.
 		tid = pr_uniquetid.GenRand32() & INT_MAX;
-		tid = FindUniqueTID(tid == 0 ? 1 : tid, 5);
+		tid = FindUniqueTID(tid == 0 ? 1 : tid, 5, clientside);
 		if (tid != 0)
 		{
 			return tid;
@@ -3621,7 +3622,7 @@ CCMD(utid)
 	for (auto Level : AllLevels())
 	{
 		Printf("%s, %d\n", Level->MapName.GetChars(), Level->FindUniqueTID(argv.argc() > 1 ? atoi(argv[1]) : 0,
-			(argv.argc() > 2 && atoi(argv[2]) >= 0) ? atoi(argv[2]) : 0));
+			(argv.argc() > 2 && atoi(argv[2]) >= 0) ? atoi(argv[2]) : 0, false));
 	}
 }
 
@@ -5113,6 +5114,7 @@ DEFINE_ACTION_FUNCTION(AActor, UpdateWaterLevel)
 
 void ConstructActor(AActor *actor, const DVector3 &pos, bool SpawningMapThing)
 {
+	const bool clientside = actor->IsClientside();
 	auto Level = actor->Level;
 	actor->SpawnTime = Level->totaltime;
 	actor->SpawnOrder = Level->spawnindex++;
@@ -5136,7 +5138,7 @@ void ConstructActor(AActor *actor, const DVector3 &pos, bool SpawningMapThing)
 	// Actors with zero gravity need the NOGRAVITY flag set.
 	if (actor->Gravity == 0) actor->flags |= MF_NOGRAVITY;
 
-	FRandom &rng = Level->BotInfo.m_Thinking ? pr_botspawnmobj : pr_spawnmobj;
+	FRandom &rng = clientside ? pr_spawncsmobj : (Level->BotInfo.m_Thinking ? pr_botspawnmobj : pr_spawnmobj);
 
 	if ((!!G_SkillProperty(SKILLP_InstantReaction) || actor->flags5 & MF5_ALWAYSFAST || !!(dmflags & DF_INSTANT_REACTION))
 		&& actor->flags3 & MF3_ISMONSTER)
@@ -5153,7 +5155,7 @@ void ConstructActor(AActor *actor, const DVector3 &pos, bool SpawningMapThing)
 	// routine, it will not be called.
 	FState *st = actor->SpawnState;
 	actor->state = st;
-	actor->tics = st->GetTics();
+	actor->tics = clientside ? st->GetClientsideTics() : st->GetTics();
 	
 	actor->sprite = st->sprite;
 	actor->frame = st->GetFrame();
@@ -5308,8 +5310,15 @@ AActor *AActor::StaticSpawn(FLevelLocals *Level, PClassActor *type, const DVecto
 
 	AActor *actor;
 
-	actor = static_cast<AActor *>(Level->CreateThinker(type));
-	actor->EnableNetworking(true);
+	if (GetDefaultByType(type)->ObjectFlags & OF_ClientSide)
+	{
+		actor = static_cast<AActor*>(Level->CreateClientsideThinker(type));
+	}
+	else
+	{
+		actor = static_cast<AActor*>(Level->CreateThinker(type));
+		actor->EnableNetworking(true);
+	}
 
 	ConstructActor(actor, pos, SpawningMapThing);
 	return actor;
@@ -5326,6 +5335,28 @@ DEFINE_ACTION_FUNCTION(AActor, Spawn)
 	ACTION_RETURN_OBJECT(AActor::StaticSpawn(currentVMLevel, type, DVector3(x, y, z), replace_t(flags)));
 }
 
+static AActor* SpawnClientside(PClassActor* type, double x, double y, double z, int flags)
+{
+	if (!(GetDefaultByType(type)->ObjectFlags & OF_ClientSide))
+	{
+		ThrowAbortException(X_OTHER, "Tried to spawn a non-clientside Actor from a clientside spawn function.");
+		return nullptr;
+	}
+
+	return AActor::StaticSpawn(currentVMLevel, type, { x, y, z }, (replace_t)flags);
+}
+
+DEFINE_ACTION_FUNCTION_NATIVE(AActor, SpawnClientside, SpawnClientside)
+{
+	PARAM_PROLOGUE;
+	PARAM_CLASS_NOT_NULL(type, AActor);
+	PARAM_FLOAT(x);
+	PARAM_FLOAT(y);
+	PARAM_FLOAT(z);
+	PARAM_INT(flags);
+	ACTION_RETURN_OBJECT(SpawnClientside(type, x, y, z, flags));
+}
+
 PClassActor *ClassForSpawn(FName classname)
 {
 	PClass *cls = PClass::FindClass(classname);
diff --git a/src/playsim/p_user.cpp b/src/playsim/p_user.cpp
index 61fd17cee..956337331 100644
--- a/src/playsim/p_user.cpp
+++ b/src/playsim/p_user.cpp
@@ -157,15 +157,6 @@ static TArray<AActor *> PredictionSectorListBackup;
 static TArray<sector_t *> PredictionTouchingSectorsBackup;
 static TArray<msecnode_t *> PredictionTouchingSectors_sprev_Backup;
 
-static TArray<sector_t *> PredictionRenderSectorsBackup;
-static TArray<msecnode_t *> PredictionRenderSectors_sprev_Backup;
-
-static TArray<sector_t *> PredictionPortalSectorsBackup;
-static TArray<msecnode_t *> PredictionPortalSectors_sprev_Backup;
-
-static TArray<FLinePortal *> PredictionPortalLinesBackup;
-static TArray<portnode_t *> PredictionPortalLines_sprev_Backup;
-
 struct
 {
 	DVector3 Pos = {};
@@ -1381,19 +1372,9 @@ void BackupNodeList(AActor *act, nodetype *head, nodetype *linktype::*otherlist,
 }
 
 template<class nodetype, class linktype>
-nodetype *RestoreNodeList(AActor *act, nodetype *head, nodetype *linktype::*otherlist, TArray<nodetype*, nodetype*> &prevbackup, TArray<linktype *, linktype *> &otherbackup)
+nodetype *RestoreNodeList(AActor *act, nodetype *linktype::*otherlist, TArray<nodetype*, nodetype*> &prevbackup, TArray<linktype *, linktype *> &otherbackup)
 {
-	// Destroy old refrences
-	nodetype *node = head;
-	while (node)
-	{
-		node->m_thing = NULL;
-		node = node->m_tnext;
-	}
-
-	// Make the sector_list match the player's touching_sectorlist before it got predicted.
-	P_DelSeclist(head, otherlist);
-	head = NULL;
+	nodetype* head = NULL;
 	for (auto i = otherbackup.Size(); i-- > 0;)
 	{
 		head = P_AddSecnode(otherbackup[i], act, head, otherbackup[i]->*otherlist);
@@ -1402,7 +1383,7 @@ nodetype *RestoreNodeList(AActor *act, nodetype *head, nodetype *linktype::*othe
 	//ctx.sector_list = NULL;		// clear for next time
 
 	// In the old code this block never executed because of the commented-out NULL assignment above. Needs to be checked
-	node = head;
+	nodetype* node = head;
 	while (node)
 	{
 		if (node->m_thing == NULL)
@@ -1496,9 +1477,6 @@ void P_PredictPlayer (player_t *player)
 	player->cheats |= CF_PREDICTING;
 
 	BackupNodeList(act, act->touching_sectorlist, &sector_t::touching_thinglist, PredictionTouchingSectors_sprev_Backup, PredictionTouchingSectorsBackup);
-	BackupNodeList(act, act->touching_rendersectors, &sector_t::touching_renderthings, PredictionRenderSectors_sprev_Backup, PredictionRenderSectorsBackup);
-	BackupNodeList(act, act->touching_sectorportallist, &sector_t::sectorportal_thinglist, PredictionPortalSectors_sprev_Backup, PredictionPortalSectorsBackup);
-	BackupNodeList(act, act->touching_lineportallist, &FLinePortal::lineportal_thinglist, PredictionPortalLines_sprev_Backup, PredictionPortalLinesBackup);
 
 	// Keep an ordered list off all actors in the linked sector.
 	PredictionSectorListBackup.Clear();
@@ -1637,15 +1615,15 @@ void P_UnPredictPlayer ()
 		// could cause it to change during prediction.
 		player->camera = savedcamera;
 
-		FLinkContext ctx;
-		// Unlink from all list, including those which are not being handled by UnlinkFromWorld.
-		auto sectorportal_list = act->touching_sectorportallist;
-		auto lineportal_list = act->touching_lineportallist;
-		act->touching_sectorportallist = nullptr;
-		act->touching_lineportallist = nullptr;
-
-		act->UnlinkFromWorld(&ctx);
+		// Unlink from all lists
+		act->UnlinkFromWorld(nullptr);
 		memcpy(&act->snext, PredictionActorBackupArray.Data(), PredictionActorBackupArray.Size() - ((uint8_t *)&act->snext - (uint8_t *)act));
+		// Clear stale pointers. The blockmap node is kept since it's the one that will be relinked back into the blockmap. Given
+		// it was removed from the list without being freed before predicting it's still valid.
+		act->touching_lineportallist = nullptr;
+		act->touching_rendersectors = act->touching_sectorlist = act->touching_sectorportallist = nullptr;
+		act->sprev = (AActor**)(size_t)0xBeefCafe;
+		act->snext = nullptr;
 
 		if (act->ViewPos != nullptr)
 		{
@@ -1678,15 +1656,15 @@ void P_UnPredictPlayer ()
 				*link = me;
 			}
 
-			act->touching_sectorlist = RestoreNodeList(act, ctx.sector_list, &sector_t::touching_thinglist, PredictionTouchingSectors_sprev_Backup, PredictionTouchingSectorsBackup);
-			act->touching_rendersectors = RestoreNodeList(act, ctx.render_list, &sector_t::touching_renderthings, PredictionRenderSectors_sprev_Backup, PredictionRenderSectorsBackup);
-			act->touching_sectorportallist = RestoreNodeList(act, sectorportal_list, &sector_t::sectorportal_thinglist, PredictionPortalSectors_sprev_Backup, PredictionPortalSectorsBackup);
-			act->touching_lineportallist = RestoreNodeList(act, lineportal_list, &FLinePortal::lineportal_thinglist, PredictionPortalLines_sprev_Backup, PredictionPortalLinesBackup);
+			// Only the touching list actually needs to be restored to avoid impacting gameplay. The rest is just clientside fluff that can
+			// be handled by relinking.
+			act->touching_sectorlist = RestoreNodeList(act, &sector_t::touching_thinglist, PredictionTouchingSectors_sprev_Backup, PredictionTouchingSectorsBackup);
+			if (act->renderradius >= 0.0)
+				act->touching_rendersectors = P_CreateSecNodeList(act, act->RenderRadius(), nullptr, &sector_t::touching_renderthings);
 		}
 
 		// Now fix the pointers in the blocknode chain
 		FBlockNode *block = act->BlockNode;
-
 		while (block != NULL)
 		{
 			*(block->PrevActor) = block;
@@ -1697,6 +1675,8 @@ void P_UnPredictPlayer ()
 			block = block->NextBlock;
 		}
 
+		act->UpdateRenderSectorList();
+
 		actInvSel = InvSel;
 		player->inventorytics = inventorytics;
 	}
diff --git a/src/scripting/thingdef_data.cpp b/src/scripting/thingdef_data.cpp
index e17e28c35..7c301c835 100644
--- a/src/scripting/thingdef_data.cpp
+++ b/src/scripting/thingdef_data.cpp
@@ -75,6 +75,7 @@ extern float			BackbuttonAlpha;
 #define DEFINE_FLAG(prefix, name, type, variable) { (unsigned int)prefix##_##name, #name, (int)(size_t)&((type*)1)->variable - 1, sizeof(((type *)0)->variable), VARF_Native }
 #define DEFINE_PROTECTED_FLAG(prefix, name, type, variable) { (unsigned int)prefix##_##name, #name, (int)(size_t)&((type*)1)->variable - 1, sizeof(((type *)0)->variable), VARF_Native|VARF_ReadOnly|VARF_InternalAccess }
 #define DEFINE_FLAG2(symbol, name, type, variable) { (unsigned int)symbol, #name, (int)(size_t)&((type*)1)->variable - 1, sizeof(((type *)0)->variable), VARF_Native }
+#define DEFINE_PROTECTED_FLAG2(symbol, name, type, variable) { (unsigned int)symbol, #name, (int)(size_t)&((type*)1)->variable - 1, sizeof(((type *)0)->variable), VARF_Native|VARF_ReadOnly|VARF_InternalAccess }
 #define DEFINE_FLAG2_DEPRECATED(symbol, name, type, variable, version) { (unsigned int)symbol, #name, (int)(size_t)&((type*)1)->variable - 1, sizeof(((type *)0)->variable), VARF_Native|VARF_Deprecated }
 #define DEFINE_DEPRECATED_FLAG(name, version) { DEPF_##name, #name, -1, 0, VARF_Deprecated, version }
 #define DEFINE_DUMMY_FLAG(name, deprec) { DEPF_UNUSED, #name, -1, 0, deprec? VARF_Deprecated:0 }
@@ -412,6 +413,7 @@ static FFlagDef ActorFlagDefs[]=
 	DEFINE_FLAG2(BOUNCE_ModifyPitch, BOUNCEMODIFIESPITCH, AActor, BounceFlags),
 	
 	DEFINE_FLAG2(OF_Transient, NOSAVEGAME, AActor, ObjectFlags),
+	DEFINE_PROTECTED_FLAG2(OF_ClientSide, CLIENTSIDE, AActor, ObjectFlags),
 
 	// Deprecated flags which need a ZScript workaround.
 	DEFINE_DEPRECATED_FLAG(MISSILEMORE, MakeVersion(4, 13, 0)),
@@ -463,7 +465,6 @@ static FFlagDef MoreFlagDefs[] =
 	// [BB] New DECORATE network related flag defines here.
 	DEFINE_DUMMY_FLAG(NONETID, false),
 	DEFINE_DUMMY_FLAG(ALLOWCLIENTSPAWN, false),
-	DEFINE_DUMMY_FLAG(CLIENTSIDEONLY, false),
 	DEFINE_DUMMY_FLAG(SERVERSIDEONLY, false),
 };
 
diff --git a/src/scripting/vmiterators.cpp b/src/scripting/vmiterators.cpp
index ec053e5fe..730f09226 100644
--- a/src/scripting/vmiterators.cpp
+++ b/src/scripting/vmiterators.cpp
@@ -41,8 +41,8 @@ class DThinkerIterator : public DObject, public FThinkerIterator
 	DECLARE_ABSTRACT_CLASS(DThinkerIterator, DObject)
 
 public:
-	DThinkerIterator(FLevelLocals *Level, PClass *cls, int statnum = MAX_STATNUM + 1)
-		: FThinkerIterator(Level, cls, statnum)
+	DThinkerIterator(FLevelLocals *Level, PClass *cls, int statnum = MAX_STATNUM + 1, bool clientside = false)
+		: FThinkerIterator(Level, cls, statnum, clientside)
 	{
 	}
 };
@@ -62,6 +62,19 @@ DEFINE_ACTION_FUNCTION_NATIVE(DThinkerIterator, Create, CreateThinkerIterator)
 	ACTION_RETURN_OBJECT(CreateThinkerIterator(type, statnum));
 }
 
+static DThinkerIterator* CreateClientsideThinkerIterator(PClass* type, int statnum)
+{
+	return Create<DThinkerIterator>(currentVMLevel, type, statnum, true);
+}
+
+DEFINE_ACTION_FUNCTION_NATIVE(DThinkerIterator, CreateClientside, CreateClientsideThinkerIterator)
+{
+	PARAM_PROLOGUE;
+	PARAM_CLASS(type, DThinker);
+	PARAM_INT(statnum);
+	ACTION_RETURN_OBJECT(CreateClientsideThinkerIterator(type, statnum));
+}
+
 static DThinker *NextThinker(DThinkerIterator *self, bool exact)
 {
 	return self->Next(exact);
@@ -365,6 +378,19 @@ DEFINE_ACTION_FUNCTION_NATIVE(FLevelLocals, CreateActorIterator, CreateActI)
 	ACTION_RETURN_OBJECT(CreateActI(self, tid, type));
 }
 
+static DActorIterator* CreateClientSideActI(FLevelLocals* Level, int tid, PClassActor* type)
+{
+	return Create<DActorIterator>(Level->ClientSideTIDHash, type, tid);
+}
+
+DEFINE_ACTION_FUNCTION_NATIVE(FLevelLocals, CreateClientSideActorIterator, CreateClientSideActI)
+{
+	PARAM_SELF_STRUCT_PROLOGUE(FLevelLocals);
+	PARAM_INT(tid);
+	PARAM_CLASS(type, AActor);
+	ACTION_RETURN_OBJECT(CreateClientSideActI(self, tid, type));
+}
+
 static AActor *NextActI(DActorIterator *self)
 {
 	return self->Next();
diff --git a/src/scripting/vmthunks.cpp b/src/scripting/vmthunks.cpp
index a43c2f468..6ff757b96 100644
--- a/src/scripting/vmthunks.cpp
+++ b/src/scripting/vmthunks.cpp
@@ -2615,6 +2615,26 @@ DEFINE_ACTION_FUNCTION_NATIVE(FLevelLocals, setFrozen, setFrozen)
 	return 0;
 }
 
+static DThinker* CreateClientsideThinker(FLevelLocals* self, PClass* type, int statnum)
+{
+	if (type->IsDescendantOf(NAME_Actor))
+	{
+		ThrowAbortException(X_OTHER, "Clientside Actors cannot be created from this function");
+		return nullptr;
+	}
+
+	return self->CreateClientsideThinker(type, statnum);
+}
+
+DEFINE_ACTION_FUNCTION_NATIVE(FLevelLocals, CreateClientsideThinker, CreateClientsideThinker)
+{
+	PARAM_SELF_STRUCT_PROLOGUE(FLevelLocals);
+	PARAM_POINTER_NOT_NULL(type, PClass);
+	PARAM_INT(statnum);
+
+	ACTION_RETURN_OBJECT(CreateClientsideThinker(self, type, statnum));
+}
+
 //=====================================================================================
 //
 //
diff --git a/src/scripting/vmthunks_actors.cpp b/src/scripting/vmthunks_actors.cpp
index 018025577..f5efbab3a 100644
--- a/src/scripting/vmthunks_actors.cpp
+++ b/src/scripting/vmthunks_actors.cpp
@@ -999,9 +999,9 @@ DEFINE_ACTION_FUNCTION_NATIVE(AActor, GetFloorTerrain, GetFloorTerrain)
 	ACTION_RETURN_POINTER(GetFloorTerrain(self));
 }
 
-static int P_FindUniqueTID(FLevelLocals *Level, int start, int limit)
+static int P_FindUniqueTID(FLevelLocals *Level, int start, int limit, bool clientside)
 {
-	return Level->FindUniqueTID(start, limit);
+	return Level->FindUniqueTID(start, limit, clientside);
 }
 
 DEFINE_ACTION_FUNCTION_NATIVE(FLevelLocals, FindUniqueTid, P_FindUniqueTID)
@@ -1009,7 +1009,8 @@ DEFINE_ACTION_FUNCTION_NATIVE(FLevelLocals, FindUniqueTid, P_FindUniqueTID)
 	PARAM_SELF_STRUCT_PROLOGUE(FLevelLocals);
 	PARAM_INT(start);
 	PARAM_INT(limit);
-	ACTION_RETURN_INT(P_FindUniqueTID(self, start, limit));
+	PARAM_BOOL(clientside);
+	ACTION_RETURN_INT(P_FindUniqueTID(self, start, limit, clientside));
 }
 
 static void RemoveFromHash(AActor *self)
diff --git a/wadsrc/static/zscript/actors/actor.zs b/wadsrc/static/zscript/actors/actor.zs
index c27dbf8ba..31b44fa1d 100644
--- a/wadsrc/static/zscript/actors/actor.zs
+++ b/wadsrc/static/zscript/actors/actor.zs
@@ -786,6 +786,7 @@ class Actor : Thinker native
 	native bool CheckPosition(Vector2 pos, bool actorsonly = false, FCheckPosition tm = null);
 	native bool TestMobjLocation();
 	native static Actor Spawn(class<Actor> type, vector3 pos = (0,0,0), int replace = NO_REPLACE);
+	native static clearscope Actor SpawnClientside(class<Actor> type, vector3 pos = (0,0,0), int replace = NO_REPLACE);
 	native Actor SpawnMissile(Actor dest, class<Actor> type, Actor owner = null);
 	native Actor SpawnMissileXYZ(Vector3 pos, Actor dest, Class<Actor> type, bool checkspawn = true, Actor owner = null);
 	native Actor SpawnMissileZ (double z, Actor dest, class<Actor> type);
diff --git a/wadsrc/static/zscript/doombase.zs b/wadsrc/static/zscript/doombase.zs
index c4582c15e..9a3e9fe04 100644
--- a/wadsrc/static/zscript/doombase.zs
+++ b/wadsrc/static/zscript/doombase.zs
@@ -140,9 +140,6 @@ extend class Object
 	native static void MarkSound(Sound snd);
 	native static uint BAM(double angle);
 	native static void SetMusicVolume(float vol);
-	native clearscope static Object GetNetworkEntity(uint id);
-	native play void EnableNetworking(bool enable);
-	native clearscope uint GetNetworkID() const;
 }
 
 class Thinker : Object native play
@@ -199,6 +196,7 @@ class Thinker : Object native play
 class ThinkerIterator : Object native
 {
 	native static ThinkerIterator Create(class<Object> type = "Actor", int statnum=Thinker.MAX_STATNUM+1);
+	native static ThinkerIterator CreateClientside(class<Thinker> type = "Actor", int statnum=Thinker.MAX_STATNUM+1);
 	native Thinker Next(bool exact = false);
 	native void Reinit();
 }
@@ -499,7 +497,7 @@ struct LevelLocals native
 	native bool IsFreelookAllowed() const;
 	native void StartIntermission(Name type, int state) const;
 	native play SpotState GetSpotState(bool create = true);
-	native int FindUniqueTid(int start = 0, int limit = 0);
+	native int FindUniqueTid(int start = 0, int limit = 0, bool clientside = false);
 	native uint GetSkyboxPortal(Actor actor);
 	native void ReplaceTextures(String from, String to, int flags);
     clearscope native HealthGroup FindHealthGroup(int id);
@@ -535,9 +533,11 @@ struct LevelLocals native
 	native void ChangeSky(TextureID sky1, TextureID sky2 );
 	native void ForceLightning(int mode = 0, sound tempSound = "");
 
+	native clearscope Thinker CreateClientsideThinker(class<Thinker> type, int statnum = Thinker.STAT_DEFAULT);
 	native SectorTagIterator CreateSectorTagIterator(int tag, line defline = null);
 	native LineIdIterator CreateLineIdIterator(int tag);
 	native ActorIterator CreateActorIterator(int tid, class<Actor> type = "Actor");
+	native ActorIterator CreateClientSideActorIterator(int tid, class<Actor> type = "Actor");
 
 	String TimeFormatted(bool totals = false)
 	{
diff --git a/wadsrc/static/zscript/engine/base.zs b/wadsrc/static/zscript/engine/base.zs
index 33c14eef6..04789cdd4 100644
--- a/wadsrc/static/zscript/engine/base.zs
+++ b/wadsrc/static/zscript/engine/base.zs
@@ -779,6 +779,11 @@ class Object native
 
 	native static Function<void> FindFunction(Class<Object> cls, Name fn);
 
+	native clearscope static Object GetNetworkEntity(uint id);
+	native play void EnableNetworking(bool enable);
+	native clearscope uint GetNetworkID() const;
+	native clearscope bool IsClientside() const;
+
 	native virtualscope void Destroy();
 
 	// This does not call into the native method of the same name to avoid problems with objects that get garbage collected late on shutdown.