diff --git a/src/common/2d/v_draw.cpp b/src/common/2d/v_draw.cpp
index a70d47e5f..87600541c 100644
--- a/src/common/2d/v_draw.cpp
+++ b/src/common/2d/v_draw.cpp
@@ -390,7 +390,9 @@ bool SetTextureParms(F2DDrawer * drawer, DrawParms *parms, FTexture *img, double
 			double srcwidth = img->GetDisplayWidthDouble();
 			double srcheight = img->GetDisplayHeightDouble();
 			int autoaspect = parms->fsscalemode;
-			aspect = autoaspect == 0 || (srcwidth == 320 && srcheight == 200) || (srcwidth == 640 && srcheight == 400)? 1.333 : srcwidth / srcheight;
+			if (srcheight == 200) aspect = srcwidth / 240.;
+			else if (srcheight == 400) aspect = srcwidth / 480;
+			else aspect = srcwidth / srcheight;
 			parms->x = parms->y = 0;
 			parms->keepratio = true;
 			auto screenratio = ActiveRatio(GetWidth(), GetHeight());
diff --git a/src/common/console/c_bind.cpp b/src/common/console/c_bind.cpp
index f4802b1e5..609f2bf86 100644
--- a/src/common/console/c_bind.cpp
+++ b/src/common/console/c_bind.cpp
@@ -720,6 +720,7 @@ void C_SetDefaultKeys(const char* baseconfig)
 		ReadBindings(lump, true);
 	}
 
+	lastlump = 0;
 	while ((lump = fileSystem.FindLump("DEFBINDS", &lastlump)) != -1)
 	{
 		ReadBindings(lump, false);
diff --git a/src/common/utility/cmdlib.cpp b/src/common/utility/cmdlib.cpp
index 3e108492d..dac58292a 100644
--- a/src/common/utility/cmdlib.cpp
+++ b/src/common/utility/cmdlib.cpp
@@ -73,7 +73,7 @@ static inline bool IsSeperator (int c)
 	if (c == '/')
 		return true;
 #ifdef _WIN32
-	if (c == '\\' || c == ':')
+	if (c == '\\')
 		return true;
 #endif
 	return false;
diff --git a/src/d_iwad.cpp b/src/d_iwad.cpp
index 21c989886..a4876ac10 100644
--- a/src/d_iwad.cpp
+++ b/src/d_iwad.cpp
@@ -263,6 +263,8 @@ void FIWadManager::ParseIWadInfo(const char *fn, const char *data, int datasize,
 // Look for IWAD definition lump
 //
 //==========================================================================
+extern const char* iwad_folders[13];
+extern const char* iwad_reserved[12];
 
 FIWadManager::FIWadManager(const char *firstfn, const char *optfn)
 {
@@ -281,10 +283,6 @@ FIWadManager::FIWadManager(const char *firstfn, const char *optfn)
 			ParseIWadInfo("IWADINFO", (const char*)data.Data(), data.Size());
 		}
 	}
-	if (mIWadNames.Size() == 0 || mIWadInfos.Size() == 0)
-	{
-		I_FatalError("No IWAD definitions found");
-	}
 }
 
 
@@ -352,7 +350,13 @@ int FIWadManager::CheckIWADInfo(const char* fn)
 {
 	FileSystem check;
 
-	check.InitSingleFile(fn, true);
+	LumpFilterInfo lfi;
+	for (auto p : iwad_folders) lfi.reservedFolders.Push(p);
+	for (auto p : iwad_reserved) lfi.requiredPrefixes.Push(p);
+
+	TArray<FString> filenames;
+	filenames.Push(fn);
+	check.InitMultipleFiles(filenames, true, &lfi);
 	if (check.GetNumEntries() > 0)
 	{
 		int num = check.CheckNumForName("IWADINFO");
@@ -372,6 +376,9 @@ int FIWadManager::CheckIWADInfo(const char* fn)
 						return i;
 					}
 				}
+
+				mOrderNames.Push(result.Name);
+				return mIWadInfos.Push(result);
 			}
 			catch (CRecoverableError & err)
 			{
diff --git a/src/d_main.cpp b/src/d_main.cpp
index 9282f0fdb..bf2eb02df 100644
--- a/src/d_main.cpp
+++ b/src/d_main.cpp
@@ -185,6 +185,9 @@ extern bool M_DemoNoPlay;	// [RH] if true, then skip any demos in the loop
 extern bool insave;
 extern TDeletingArray<FLightDefaults *> LightDefaults;
 
+const char* iwad_folders[13] = { "flats/", "textures/", "hires/", "sprites/", "voxels/", "colormaps/", "acs/", "maps/", "voices/", "patches/", "graphics/", "sounds/", "music/" };
+const char* iwad_reserved[12] = { "mapinfo", "zmapinfo", "gameinfo", "sndinfo", "sbarinfo", "menudef", "gldefs", "animdefs", "decorate", "zscript", "iwadinfo" "maps/" };
+
 
 CUSTOM_CVAR(Float, i_timescale, 1.0f, CVAR_NOINITCALL)
 {
@@ -1854,8 +1857,12 @@ static FString CheckGameInfo(TArray<FString> & pwads)
 {
 	FileSystem check;
 
+	LumpFilterInfo lfi;
+	for (auto p : iwad_folders) lfi.reservedFolders.Push(p);
+	for (auto p : iwad_reserved) lfi.requiredPrefixes.Push(p);
+
 	// Open the entire list as a temporary file system and look for a GAMEINFO lump. The last one will automatically win.
-	check.InitMultipleFiles(pwads, true);
+	check.InitMultipleFiles(pwads, true, &lfi);
 	if (check.GetNumEntries() > 0)
 	{
 		int num = check.CheckNumForName("GAMEINFO");
@@ -2993,11 +3000,8 @@ static int D_DoomMain_Internal (void)
 		}
 		lfi.gameTypeFilter.Push(FStringf("game-%s", GameTypeName()));
 
-		static const char* folders[] = { "flats/", "textures/", "hires/", "sprites/", "voxels/", "colormaps/", "acs/", "maps/", "voices/", "patches/", "graphics/", "sounds/", "music/" };
-		for (auto p : folders) lfi.reservedFolders.Push(p);
-
-		static const char* reserved[] = { "mapinfo", "zmapinfo", "gameinfo", "sndinfo", "sbarinfo", "menudef", "gldefs", "animdefs", "decorate", "zscript", "maps/" };
-		for (auto p : reserved) lfi.requiredPrefixes.Push(p);
+		for (auto p : iwad_folders) lfi.reservedFolders.Push(p);
+		for (auto p : iwad_reserved) lfi.requiredPrefixes.Push(p);
 
 		lfi.postprocessFunc = [&]()
 		{
diff --git a/src/maploader/specials.cpp b/src/maploader/specials.cpp
index 64f3ea7b8..240b0818b 100644
--- a/src/maploader/specials.cpp
+++ b/src/maploader/specials.cpp
@@ -943,7 +943,8 @@ int MapLoader::Set3DFloor(line_t * line, int param, int param2, int alpha)
 			// if flooding is used the floor must be non-solid and is automatically made shootthrough and seethrough
 			if ((param2 & 128) && !(flags & FF_SOLID)) flags |= FF_FLOOD | FF_SEETHROUGH | FF_SHOOTTHROUGH;
 			if (param2 & 512) flags |= FF_FADEWALLS;
-			if (param2&1024) flags |= FF_RESET;
+			if (param2 & 1024) flags |= FF_RESET;
+			if (param2 & 2048) flags |= FF_NODAMAGE;
 			FTextureID tex = line->sidedef[0]->GetTexture(side_t::top);
 			if (!tex.Exists() && alpha < 255)
 			{
@@ -970,7 +971,7 @@ int MapLoader::Set3DFloor(line_t * line, int param, int param2, int alpha)
 
 void MapLoader::Spawn3DFloors ()
 {
-	static int flagvals[] = {512, 2+512, 512+1024};
+	static int flagvals[] = {512+2048, 2+512+2048, 512+1024+2048};
 
 	for (auto &line : Level->lines)
 	{
diff --git a/src/menu/loadsavemenu.cpp b/src/menu/loadsavemenu.cpp
index 6811ef4b8..25bc4b16b 100644
--- a/src/menu/loadsavemenu.cpp
+++ b/src/menu/loadsavemenu.cpp
@@ -504,7 +504,6 @@ unsigned FSavegameManager::ExtractSaveData(int index)
 					{
 						delete SavePic;
 						SavePic = nullptr;
-						SavePicData.Clear();
 					}
 				}
 			}
@@ -536,7 +535,6 @@ void FSavegameManager::UnloadSaveData()
 
 	SaveCommentString = "";
 	SavePic = nullptr;
-	SavePicData.Clear();
 }
 
 DEFINE_ACTION_FUNCTION(FSavegameManager, UnloadSaveData)
diff --git a/src/menu/menu.h b/src/menu/menu.h
index 98fd2addb..ce17a188b 100644
--- a/src/menu/menu.h
+++ b/src/menu/menu.h
@@ -72,7 +72,6 @@ private:
 	FSaveGameNode NewSaveNode;
 	int LastSaved = -1;
 	int LastAccessed = -1;
-	TArray<char> SavePicData;
 	FTexture *SavePic = nullptr;
 
 public:
diff --git a/src/playsim/p_3dfloors.cpp b/src/playsim/p_3dfloors.cpp
index 7d7c60889..ece17634b 100644
--- a/src/playsim/p_3dfloors.cpp
+++ b/src/playsim/p_3dfloors.cpp
@@ -217,10 +217,11 @@ void P_PlayerOnSpecial3DFloor(player_t* player)
 			// Player must be on top of the floor to be affected...
 			if(player->mo->Z() != rover->top.plane->ZatPoint(player->mo)) continue;
 		}
-		else
+		else 
 		{
 			//Water and DEATH FOG!!! heh
-			if (player->mo->Z() > rover->top.plane->ZatPoint(player->mo) || 
+			if ((rover->flags & FF_NODAMAGE) ||
+				player->mo->Z() > rover->top.plane->ZatPoint(player->mo) ||
 				player->mo->Top() < rover->bottom.plane->ZatPoint(player->mo))
 				continue;
 		}
diff --git a/src/playsim/p_3dfloors.h b/src/playsim/p_3dfloors.h
index f0b1e87fd..05d222137 100644
--- a/src/playsim/p_3dfloors.h
+++ b/src/playsim/p_3dfloors.h
@@ -23,7 +23,7 @@ typedef enum
   FF_UPPERTEXTURE	   = 0x20000,
   FF_LOWERTEXTURE      = 0x40000,
   FF_THINFLOOR		   = 0x80000,	// EDGE
-  FF_SCROLLY           = 0x100000,  // EDGE - not yet implemented!!!
+  FF_NODAMAGE          = 0x100000,  // no damage transfers
   FF_FIX			   = 0x200000,  // use floor of model sector as floor and floor of real sector as ceiling
   FF_INVERTSECTOR	   = 0x400000,	// swap meaning of sector planes
   FF_DYNAMIC		   = 0x800000,	// created by partitioning another 3D-floor due to overlap
diff --git a/src/playsim/p_lnspec.cpp b/src/playsim/p_lnspec.cpp
index 5a3a67996..121e3402c 100644
--- a/src/playsim/p_lnspec.cpp
+++ b/src/playsim/p_lnspec.cpp
@@ -3911,6 +3911,13 @@ int P_FindLineSpecial (const char *string, int *min_args, int *max_args)
 			max = mid - 1;
 		}
 	}
+	// Alias for ZScript. Check here to have universal support everywhere.
+	if (!stricmp(string, "TeleportSpecial"))
+	{
+		if (min_args != NULL) *min_args = 1;
+		if (max_args != NULL) *max_args = 3;
+		return Teleport;
+	}
 	return 0;
 }
 
diff --git a/src/playsim/p_mobj.cpp b/src/playsim/p_mobj.cpp
index 3214be35a..a23e71ebb 100644
--- a/src/playsim/p_mobj.cpp
+++ b/src/playsim/p_mobj.cpp
@@ -5000,9 +5000,12 @@ void StaticPointerSubstitution(AActor* old, AActor* notOld)
 
 	if (old == nullptr) return;
 
-	// This is only allowed to replace players. For everything else the results are undefined.
-	if (!old->IsKindOf(NAME_PlayerPawn) || (notOld != nullptr && !notOld->IsKindOf(NAME_PlayerPawn))) return;
-
+	// This is only allowed to replace players or swap out morphed monsters
+	if (!old->IsKindOf(NAME_PlayerPawn) || (notOld != nullptr && !notOld->IsKindOf(NAME_PlayerPawn)))
+	{
+		if (notOld == nullptr) return;
+		if (!old->IsKindOf(NAME_MorphedMonster) && !notOld->IsKindOf(NAME_MorphedMonster)) return;
+	}
 	// Go through all objects.
 	i = 0; DObject* last = 0;
 	for (probe = GC::Root; probe != NULL; probe = probe->ObjNext)
diff --git a/src/rendering/hwrenderer/scene/hw_sprites.cpp b/src/rendering/hwrenderer/scene/hw_sprites.cpp
index b5611cb00..c7442a156 100644
--- a/src/rendering/hwrenderer/scene/hw_sprites.cpp
+++ b/src/rendering/hwrenderer/scene/hw_sprites.cpp
@@ -1230,7 +1230,7 @@ void HWSprite::ProcessParticle (HWDrawInfo *di, particle_t *particle, sector_t *
 	z1=z-scalefac;
 	z2=z+scalefac;
 
-	depth = FloatToFixed((x - vp.Pos.X) * vp.TanCos + (y - vp.Pos.Y) * vp.TanSin);
+	depth = (float)((x - vp.Pos.X) * vp.TanCos + (y - vp.Pos.Y) * vp.TanSin);
 
 	actor=nullptr;
 	this->particle=particle;
diff --git a/src/scripting/vmthunks_actors.cpp b/src/scripting/vmthunks_actors.cpp
index 5bb73f244..a99554ab8 100644
--- a/src/scripting/vmthunks_actors.cpp
+++ b/src/scripting/vmthunks_actors.cpp
@@ -1614,6 +1614,22 @@ DEFINE_ACTION_FUNCTION_NATIVE(AActor, Substitute, StaticPointerSubstitution)
 	return 0;
 }
 
+DEFINE_ACTION_FUNCTION_NATIVE(_PlayerPawn, Substitute, StaticPointerSubstitution)
+{
+	PARAM_SELF_PROLOGUE(AActor);
+	PARAM_OBJECT(replace, AActor);
+	StaticPointerSubstitution(self, replace);
+	return 0;
+}
+
+DEFINE_ACTION_FUNCTION_NATIVE(_MorphedMonster, Substitute, StaticPointerSubstitution)
+{
+	PARAM_SELF_PROLOGUE(AActor);
+	PARAM_OBJECT(replace, AActor);
+	StaticPointerSubstitution(self, replace);
+	return 0;
+}
+
 DEFINE_ACTION_FUNCTION_NATIVE(AActor, GetSpawnableType, P_GetSpawnableType)
 {
 	PARAM_PROLOGUE;
diff --git a/wadsrc/static/zscript/actors/actor.zs b/wadsrc/static/zscript/actors/actor.zs
index 9638d9e5f..bbd89dd44 100644
--- a/wadsrc/static/zscript/actors/actor.zs
+++ b/wadsrc/static/zscript/actors/actor.zs
@@ -461,7 +461,7 @@ class Actor : Thinker native
 	virtual native void Die(Actor source, Actor inflictor, int dmgflags = 0, Name MeansOfDeath = 'none');
 	virtual native bool Slam(Actor victim);
 	virtual native void Touch(Actor toucher);
-	native void Substitute(Actor replacement);
+	private native void Substitute(Actor replacement);
 	native ui void DisplayNameTag();
 
 	// Called by inventory items to see if this actor is capable of touching them.
diff --git a/wadsrc/static/zscript/actors/player/player_morph.zs b/wadsrc/static/zscript/actors/player/player_morph.zs
index 66fd0f1d8..391be4a06 100644
--- a/wadsrc/static/zscript/actors/player/player_morph.zs
+++ b/wadsrc/static/zscript/actors/player/player_morph.zs
@@ -1,5 +1,7 @@
 extend class PlayerPawn
 {
+	private native void Substitute(PlayerPawn replacement);
+
 	//===========================================================================
 	//
 	// EndAllPowerupEffects
@@ -503,6 +505,8 @@ class MorphedMonster : Actor
 		+FLOORCLIP
 	}
 
+	private native void Substitute(Actor replacement);
+
 	override void OnDestroy ()
 	{
 		if (UnmorphedMe != NULL)
diff --git a/wadsrc/static/zscript/mapdata.zs b/wadsrc/static/zscript/mapdata.zs
index 1ac5f12de..b681711d4 100644
--- a/wadsrc/static/zscript/mapdata.zs
+++ b/wadsrc/static/zscript/mapdata.zs
@@ -234,7 +234,8 @@ struct F3DFloor native play
 		FF_UPPERTEXTURE	 = 0x20000,
 		FF_LOWERTEXTURE  = 0x40000,
 		FF_THINFLOOR     = 0x80000,	// EDGE
-		FF_SCROLLY       = 0x100000,  // EDGE - not yet implemented!!!
+		FF_SCROLLY       = 0x100000,  // old leftover definition
+		FF_NODAMAGE      = 0x100000,  // no damage transfers
 		FF_FIX           = 0x200000,  // use floor of model sector as floor and floor of real sector as ceiling
 		FF_INVERTSECTOR  = 0x400000,	// swap meaning of sector planes
 		FF_DYNAMIC       = 0x800000,	// created by partitioning another 3D-floor due to overlap