diff --git a/src/info.cpp b/src/info.cpp
index 81912150b..84d8e26be 100644
--- a/src/info.cpp
+++ b/src/info.cpp
@@ -257,6 +257,7 @@ PClassActor::PClassActor()
 	WoundHealth = 6;
 	FastSpeed = -1.;
 	RDFactor = 1.;
+	SelfDamageFactor = 1.;
 	CameraHeight = INT_MIN;
 
 	DropItems = NULL;
@@ -317,6 +318,7 @@ void PClassActor::DeriveData(PClass *newclass)
 	newa->WoundHealth = WoundHealth;
 	newa->FastSpeed = FastSpeed;
 	newa->RDFactor = RDFactor;
+	newa->SelfDamageFactor = SelfDamageFactor;
 	newa->CameraHeight = CameraHeight;
 	newa->HowlSound = HowlSound;
 	newa->BloodType = BloodType;
diff --git a/src/info.h b/src/info.h
index 50db1e4b6..a9f79182f 100644
--- a/src/info.h
+++ b/src/info.h
@@ -299,6 +299,7 @@ public:
 	int WoundHealth;		// Health needed to enter wound state
 	double FastSpeed;		// speed in fast mode
 	double RDFactor;		// Radius damage factor
+	double SelfDamageFactor;
 	double CameraHeight;	// Height of camera when used as such
 	FSoundID HowlSound;		// Sound being played when electrocuted or poisoned
 	FName BloodType;		// Blood replacement type
diff --git a/src/menu/menudef.cpp b/src/menu/menudef.cpp
index dc4fff1a7..239366dcf 100644
--- a/src/menu/menudef.cpp
+++ b/src/menu/menudef.cpp
@@ -871,6 +871,25 @@ static void ParseOptionMenu(FScanner &sc)
 }
 
 
+//=============================================================================
+//
+//
+//
+//=============================================================================
+
+static void ParseAddOptionMenu(FScanner &sc)
+{
+	sc.MustGetString();
+
+	DMenuDescriptor **pOld = MenuDescriptors.CheckKey(sc.String);
+	if (pOld == nullptr || *pOld == nullptr || !(*pOld)->IsKindOf(RUNTIME_CLASS(DOptionMenuDescriptor)))
+	{
+		sc.ScriptError("%s is not an option menu that can be extended", sc.String);
+	}
+	ParseOptionMenuBody(sc, (DOptionMenuDescriptor*)(*pOld));
+}
+
+
 //=============================================================================
 //
 //
@@ -935,6 +954,10 @@ void M_ParseMenuDefs()
 			{
 				ParseOptionMenu(sc);
 			}
+			else if (sc.Compare("ADDOPTIONMENU"))
+			{
+				ParseAddOptionMenu(sc);
+			}
 			else if (sc.Compare("DEFAULTOPTIONMENU"))
 			{
 				ParseOptionMenuBody(sc, DefaultOptionMenuSettings);
diff --git a/src/p_interaction.cpp b/src/p_interaction.cpp
index 38d9cd375..4c23c8123 100644
--- a/src/p_interaction.cpp
+++ b/src/p_interaction.cpp
@@ -1020,6 +1020,11 @@ static int DamageMobj (AActor *target, AActor *inflictor, AActor *source, int da
 		}
 		return 0;
 	}
+	if (target == source && damage < TELEFRAG_DAMAGE)
+	{
+		damage = int(damage * target->GetClass()->SelfDamageFactor);
+	}
+
 	// [MC] Changed it to check rawdamage here for consistency, even though that doesn't actually do anything
 	// different here. At any rate, invulnerable is being checked before type factoring, which is then being 
 	// checked by player cheats/invul/buddha followed by monster buddha. This is inconsistent. Don't let the 
diff --git a/src/p_map.cpp b/src/p_map.cpp
index 9b3a257ec..70b18df7f 100644
--- a/src/p_map.cpp
+++ b/src/p_map.cpp
@@ -2281,9 +2281,9 @@ bool P_TryMove(AActor *thing, const DVector2 &pos,
 			}
 #endif
 		}
-		if (!(thing->flags & MF_TELEPORT) && !(thing->flags3 & MF3_FLOORHUGGER))
+		if (!(thing->flags & MF_TELEPORT) && (!(thing->flags3 & MF3_FLOORHUGGER) || thing->flags5 & MF5_NODROPOFF))
 		{
-			if ((thing->flags & MF_MISSILE) && !(thing->flags6 & MF6_STEPMISSILE) && tm.floorz > thing->Z())
+			if ((thing->flags & MF_MISSILE) && !(thing->flags6 & MF6_STEPMISSILE) && tm.floorz > thing->Z() && !(thing->flags3 & MF3_FLOORHUGGER))
 			{ // [RH] Don't let normal missiles climb steps
 				goto pushline;
 			}
@@ -2772,13 +2772,13 @@ bool P_CheckMove(AActor *thing, const DVector2 &pos, int flags)
 			if (thing->Top() > tm.ceilingz)
 				return false;
 		}
-		if (!(thing->flags & MF_TELEPORT) && !(thing->flags3 & MF3_FLOORHUGGER))
+		if (!(thing->flags & MF_TELEPORT) && (!(thing->flags3 & MF3_FLOORHUGGER) || thing->flags5 & MF5_NODROPOFF))
 		{
 			if (tm.floorz - newz > thing->MaxStepHeight)
 			{ // too big a step up
 				return false;
 			}
-			else if ((thing->flags & MF_MISSILE) && !(thing->flags6 & MF6_STEPMISSILE) && tm.floorz > newz)
+			else if ((thing->flags & MF_MISSILE) && !(thing->flags6 & MF6_STEPMISSILE) && tm.floorz > newz && !(thing->flags3 & MF3_FLOORHUGGER))
 			{ // [RH] Don't let normal missiles climb steps
 				return false;
 			}
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index d6da38961..f85f2c9eb 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -321,6 +321,7 @@ DEFINE_FIELD(PClassActor, GibHealth)
 DEFINE_FIELD(PClassActor, WoundHealth)
 DEFINE_FIELD(PClassActor, FastSpeed)
 DEFINE_FIELD(PClassActor, RDFactor)
+DEFINE_FIELD(PClassActor, SelfDamageFactor)
 DEFINE_FIELD(PClassActor, CameraHeight)
 DEFINE_FIELD(PClassActor, HowlSound)
 DEFINE_FIELD(PClassActor, BloodType)
@@ -2958,7 +2959,7 @@ void P_ZMovement (AActor *mo, double oldfloorz)
 					mo->Vel.Z = 0;
 					return;
 				}
-				else if (mo->flags3 & MF3_FLOORHUGGER)
+				else if ((mo->flags3 & MF3_FLOORHUGGER) && !(mo->flags5 & MF5_NODROPOFF))
 				{ // Floor huggers can go up steps
 					return;
 				}
diff --git a/src/scripting/thingdef_properties.cpp b/src/scripting/thingdef_properties.cpp
index 50b81310c..6537e2482 100644
--- a/src/scripting/thingdef_properties.cpp
+++ b/src/scripting/thingdef_properties.cpp
@@ -1430,6 +1430,16 @@ DEFINE_PROPERTY(radiusdamagefactor, F, Actor)
 	static_cast<PClassActor *>(info)->RDFactor = i;
 }
 
+//==========================================================================
+//
+//==========================================================================
+DEFINE_PROPERTY(selfdamagefactor, F, Actor)
+{
+	PROP_DOUBLE_PARM(i, 0);
+	assert(info->IsKindOf(RUNTIME_CLASS(PClassActor)));
+	static_cast<PClassActor *>(info)->SelfDamageFactor = i;
+}
+
 //==========================================================================
 //
 //==========================================================================