diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index 31ba7c94f..1012ddb6a 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,4 +1,13 @@
 June 9, 2009  (Changes by Graf Zahl)
+- Added Gez's Skulltag feature patch, including:
+    * BUMPSPECIAL flag: actors with this flag will run their special if collided on by a player
+    * WEAPON.NOAUTOAIM flag, though it is restricted to attacks that spawn a missile (it will 
+	  not affect autoaim settings for a hitscan or railgun, and that's deliberate)
+    * A_FireSTGrenade codepointer, extended to be parameterizable
+    * The grenade (as the default actor for A_FireSTGrenade)
+    * Protective armors à la RedArmor: they work with a DamageFactor; for example to 
+	  recreate the RedArmor from Skulltag, copy its code from skulltag.pk3 but remove 
+	  the "native" keyword and add DamageFactor "Fire" 0.1 to its properties.
 - Fixed: I_ShutdownInput must NULL all pointers because it can be called twice
   if an ENDOOM screen is displayed.
 - Fixed: R_DrawSkyStriped used frontyScale without initializing it first.
diff --git a/src/actor.h b/src/actor.h
index 62851f7f4..d36fe321a 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -309,6 +309,7 @@ enum
 	MF6_MTHRUSPECIES	= 0x00000004,	// Missile passes through actors of its shooter's species.
 	MF6_FORCEPAIN		= 0x00000008,	// forces target into painstate (unless it has the NOPAIN flag)
 	MF6_NOFEAR			= 0x00000010,	// Not scared of frightening players
+	MF6_BUMPSPECIAL		= 0x00000020,	// Actor executes its special when being collided (as the ST flag)
 
 
 // --- mobj.renderflags ---
diff --git a/src/g_doom/a_doomweaps.cpp b/src/g_doom/a_doomweaps.cpp
index 39128fdfe..71ae8cb96 100644
--- a/src/g_doom/a_doomweaps.cpp
+++ b/src/g_doom/a_doomweaps.cpp
@@ -361,6 +361,34 @@ DEFINE_ACTION_FUNCTION(AActor, A_FireMissile)
 	P_SpawnPlayerMissile (self, PClass::FindClass("Rocket"));
 }
 
+//
+// A_FireSTGrenade: not exactly backported from ST, but should work the same
+//
+DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_FireSTGrenade)
+{
+	player_t *player;
+	ACTION_PARAM_START(1);
+	ACTION_PARAM_CLASS(grenade, 0);
+	if (grenade == NULL) return;
+
+	if (NULL == (player = self->player))
+	{
+		return;
+	}
+	AWeapon *weapon = self->player->ReadyWeapon;
+	if (weapon != NULL)
+	{
+		if (!weapon->DepleteAmmo (weapon->bAltFire))
+			return;
+	}
+		
+	// Temporarily raise the pitch to send the grenade slightly upwards
+	fixed_t SavedPlayerPitch = self->pitch;
+	self->pitch -= (1152 << FRACBITS);
+	P_SpawnPlayerMissile(self, grenade);
+	self->pitch = SavedPlayerPitch;
+}
+
 //
 // A_FirePlasma
 //
diff --git a/src/g_shared/a_armor.cpp b/src/g_shared/a_armor.cpp
index 61605f86f..cf3745e2a 100644
--- a/src/g_shared/a_armor.cpp
+++ b/src/g_shared/a_armor.cpp
@@ -139,6 +139,7 @@ void ABasicArmor::AbsorbDamage (int damage, FName damageType, int &newdamage)
 		{
 			// The armor has become useless
 			SavePercent = 0;
+			ArmorType = NAME_None; // Not NAME_BasicArmor.
 			// Now see if the player has some more armor in their inventory
 			// and use it if so. As in Strife, the best armor is used up first.
 			ABasicArmorPickup *best = NULL;
@@ -162,6 +163,24 @@ void ABasicArmor::AbsorbDamage (int damage, FName damageType, int &newdamage)
 		}
 		damage = newdamage;
 	}
+
+	// Once the armor has absorbed its part of the damage, then apply its damage factor, if any, to the player
+	if ((damage > 0) && (ArmorType != NAME_None)) // BasicArmor is not going to have any damage factor, so skip it.
+	{
+		// This code is taken and adapted from APowerProtection::ModifyDamage().
+		// The differences include not checking for the NAME_None key (doesn't seem appropriate here), 
+		// not using a default value, and of course the way the damage factor info is obtained.
+		const fixed_t *pdf = NULL;
+		DmgFactors *df = PClass::FindClass(ArmorType)->ActorInfo->DamageFactors;
+		if (df != NULL && df->CountUsed() != 0)
+		{
+			pdf = df->CheckKey(damageType);
+			if (pdf != NULL)
+			{
+				damage = newdamage = FixedMul(damage, *pdf);
+			}
+		}
+	}
 	if (Inventory != NULL)
 	{
 		Inventory->AbsorbDamage (damage, damageType, newdamage);
diff --git a/src/g_shared/a_pickups.cpp b/src/g_shared/a_pickups.cpp
index bdff394f2..9a29d2d38 100644
--- a/src/g_shared/a_pickups.cpp
+++ b/src/g_shared/a_pickups.cpp
@@ -1387,7 +1387,7 @@ IMPLEMENT_CLASS (AHealth)
 
 //===========================================================================
 //
-// AHealth :: TryPickup
+// AHealth :: PickupMessage
 //
 //===========================================================================
 const char *AHealth::PickupMessage ()
diff --git a/src/g_shared/a_pickups.h b/src/g_shared/a_pickups.h
index ef100357e..f48289cbb 100644
--- a/src/g_shared/a_pickups.h
+++ b/src/g_shared/a_pickups.h
@@ -317,9 +317,10 @@ enum
 	WIF_POWERED_UP =		0x00000400, // this is a tome-of-power'ed version of its sister
 	WIF_AMMO_CHECKBOTH =	0x00000800, // check for both primary and secondary fire before switching it off
 	WIF_NO_AUTO_SWITCH =	0x00001000,	// never switch to this weapon when it's picked up
-	WIF_STAFF2_KICKBACK =	0x00002000, // the powered-up Heretic staff has special kickba
+	WIF_STAFF2_KICKBACK =	0x00002000, // the powered-up Heretic staff has special kickback
+	WIF_NOAUTOAIM =			0x00004000, // this weapon never uses autoaim (useful for ballistic projectiles)
 
-	WIF_CHEATNOTWEAPON	=	1<<27,		// Give cheat considers this not a weapon (used by Sigil)
+	WIF_CHEATNOTWEAPON	=	0x08000000,	// Give cheat considers this not a weapon (used by Sigil)
 
 	// Flags used only by bot AI:
 
diff --git a/src/p_acs.cpp b/src/p_acs.cpp
index 5f8d42a9c..903cf1efc 100644
--- a/src/p_acs.cpp
+++ b/src/p_acs.cpp
@@ -2957,7 +2957,7 @@ int DLevelScript::CallFunction(int argCount, int funcIndex, SDWORD *args)
 			{
 				FName p(FBehavior::StaticLookupString(args[0]));
 				ABasicArmor * armor = (ABasicArmor *) players[args[1]].mo->FindInventory(NAME_BasicArmor);
-				if (armor->ArmorType == p) return 1;
+				if (armor && armor->ArmorType == p) return armor->Amount;
 			}
 			return 0;
 		}
diff --git a/src/p_map.cpp b/src/p_map.cpp
index f1ef571af..27a32e639 100644
--- a/src/p_map.cpp
+++ b/src/p_map.cpp
@@ -826,6 +826,13 @@ bool PIT_CheckThing (AActor *thing, FCheckPosition &tm)
 			return false;
 		}
 	}
+	// Check for players touching a thing with MF6_BUMPSPECIAL
+	// A blind recreation of what the Skulltag code is probably like.
+	if (tm.thing->player && (thing->flags6 & MF6_BUMPSPECIAL) && thing->special)
+	{
+		LineSpecials[thing->special] (NULL, tm.thing, false, thing->args[0], 
+			thing->args[1], thing->args[2], thing->args[3], thing->args[4]);
+	}
 	// Check for missile
 	if (tm.thing->flags & MF_MISSILE)
 	{
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index f838930f1..458997b61 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -4999,21 +4999,30 @@ AActor *P_SpawnPlayerMissile (AActor *source, fixed_t x, fixed_t y, fixed_t z,
 	AActor *linetarget;
 	int vrange = nofreeaim? ANGLE_1*35 : 0;
 
-	// see which target is to be aimed at
-	i = 2;
-	do
+	// Note: NOAUTOAIM is implemented only here, and not in the hitscan or rail attack functions.
+	// That is because it is only justified for projectiles affected by gravity, not for other attacks.
+	if (source && source->player && source->player->ReadyWeapon && (source->player->ReadyWeapon->WeaponFlags & WIF_NOAUTOAIM))
 	{
-		an = angle + angdiff[i];
-		pitch = P_AimLineAttack (source, an, 16*64*FRACUNIT, &linetarget, vrange);
-
-		if (source->player != NULL &&
-			!nofreeaim &&
-			level.IsFreelookAllowed() &&
-			source->player->userinfo.GetAimDist() <= ANGLE_1/2)
+		// Keep exactly the same angle and pitch as the player's own aim
+		pitch = source->pitch; linetarget = NULL;
+	}
+	else // see which target is to be aimed at
+	{
+		i = 2;
+		do
 		{
-			break;
-		}
-	} while (linetarget == NULL && --i >= 0);
+			an = angle + angdiff[i];
+			pitch = P_AimLineAttack (source, an, 16*64*FRACUNIT, &linetarget, vrange);
+	
+			if (source->player != NULL &&
+				!nofreeaim &&
+				level.IsFreelookAllowed() &&
+				source->player->userinfo.GetAimDist() <= ANGLE_1/2)
+			{
+				break;
+			}
+		} while (linetarget == NULL && --i >= 0);
+	}
 
 	if (linetarget == NULL)
 	{
diff --git a/src/thingdef/thingdef_codeptr.cpp b/src/thingdef/thingdef_codeptr.cpp
index d9a14e425..02108f7fb 100644
--- a/src/thingdef/thingdef_codeptr.cpp
+++ b/src/thingdef/thingdef_codeptr.cpp
@@ -535,12 +535,13 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_JumpIfArmorType)
 	ACTION_PARAM_START(3);
 	ACTION_PARAM_NAME(Type, 0);
 	ACTION_PARAM_STATE(JumpOffset, 1);
+	ACTION_PARAM_INT(amount, 1);
 
 	ACTION_SET_RESULT(false);	// Jumps should never set the result for inventory state chains!
 
 	ABasicArmor * armor = (ABasicArmor *) self->FindInventory(NAME_BasicArmor);
 
-	if (armor && armor->ArmorType == Type)
+	if (armor && armor->ArmorType == Type && armor->Amount >= amount)
 		ACTION_JUMP(JumpOffset);
 }
 
diff --git a/src/thingdef/thingdef_data.cpp b/src/thingdef/thingdef_data.cpp
index 986135592..cf77825a1 100644
--- a/src/thingdef/thingdef_data.cpp
+++ b/src/thingdef/thingdef_data.cpp
@@ -214,6 +214,7 @@ static FFlagDef ActorFlags[]=
 	DEFINE_FLAG(MF6, MTHRUSPECIES, AActor, flags6),
 	DEFINE_FLAG(MF6, FORCEPAIN, AActor, flags6),
 	DEFINE_FLAG(MF6, NOFEAR, AActor, flags6),
+	DEFINE_FLAG(MF6, BUMPSPECIAL, AActor, flags6),
 
 	// Effect flags
 	DEFINE_FLAG(FX, VISIBILITYPULSE, AActor, effects),
@@ -234,9 +235,12 @@ static FFlagDef ActorFlags[]=
 	DEFINE_DEPRECATED_FLAG(HERETICBOUNCE),
 	DEFINE_DEPRECATED_FLAG(HEXENBOUNCE),
 	DEFINE_DEPRECATED_FLAG(DOOMBOUNCE),
-	DEFINE_DUMMY_FLAG(NONETID),
-	DEFINE_DUMMY_FLAG(ALLOWCLIENTSPAWN),
-	DEFINE_DUMMY_FLAG(CLIENTSIDEONLY),
+
+// Various Skulltag flags that are quite irrelevant to ZDoom
+	DEFINE_DUMMY_FLAG(NONETID),				// netcode-based
+	DEFINE_DUMMY_FLAG(ALLOWCLIENTSPAWN),	// netcode-based
+	DEFINE_DUMMY_FLAG(CLIENTSIDEONLY),	    // netcode-based
+	DEFINE_DUMMY_FLAG(EXPLODEONDEATH),	    // seems useless
 };
 
 static FFlagDef InventoryFlags[] =
@@ -281,6 +285,7 @@ static FFlagDef WeaponFlags[] =
 	DEFINE_FLAG(WIF, CHEATNOTWEAPON, AWeapon, WeaponFlags),
 	DEFINE_FLAG(WIF, NO_AUTO_SWITCH, AWeapon, WeaponFlags),
 	DEFINE_FLAG(WIF, AMMO_CHECKBOTH, AWeapon, WeaponFlags),
+	DEFINE_FLAG(WIF, NOAUTOAIM, AWeapon, WeaponFlags),
 	
 	DEFINE_DUMMY_FLAG(NOLMS),
 };
diff --git a/src/thingdef/thingdef_parse.cpp b/src/thingdef/thingdef_parse.cpp
index bfe1023ee..68fe77fe2 100644
--- a/src/thingdef/thingdef_parse.cpp
+++ b/src/thingdef/thingdef_parse.cpp
@@ -60,7 +60,7 @@ void ParseOldDecoration(FScanner &sc, EDefinitionType def);
 //
 // ParseParameter
 //
-// Parses aparameter - either a default in a function declaration 
+// Parses a parameter - either a default in a function declaration 
 // or an argument in a function call.
 //
 //==========================================================================
diff --git a/src/thingdef/thingdef_properties.cpp b/src/thingdef/thingdef_properties.cpp
index fc2765a49..9d56c7d07 100644
--- a/src/thingdef/thingdef_properties.cpp
+++ b/src/thingdef/thingdef_properties.cpp
@@ -1262,6 +1262,14 @@ DEFINE_CLASS_PROPERTY(pickupsound, S, Inventory)
 	defaults->PickupSound = str;
 }
 
+//==========================================================================
+// Dummy for Skulltag compatibility...
+//==========================================================================
+DEFINE_CLASS_PROPERTY(pickupannouncerentry, S, Inventory)
+{
+	PROP_STRING_PARM(str, 0);
+}
+
 //==========================================================================
 //
 //==========================================================================
diff --git a/wadsrc/static/actors/actor.txt b/wadsrc/static/actors/actor.txt
index e758214fe..295672d93 100644
--- a/wadsrc/static/actors/actor.txt
+++ b/wadsrc/static/actors/actor.txt
@@ -176,7 +176,7 @@ ACTOR Actor native //: Thinker
 	action native A_JumpIfHealthLower(int health, state label);
 	action native A_JumpIfCloser(float distance, state label);
 	action native A_JumpIfInventory(class<Inventory> itemtype, int itemamount, state label);
-	action native A_JumpIfArmorType(string Type, state label);
+	action native A_JumpIfArmorType(string Type, state label, int amount = 1);
 	action native A_GiveInventory(class<Inventory> itemtype, int amount = 0);
 	action native A_TakeInventory(class<Inventory> itemtype, int amount = 0);
 	action native A_SpawnItem(class<Actor> itemtype, float distance = 0, float zheight = 0, bool useammo = true, bool transfer_translation = false);
diff --git a/wadsrc/static/actors/doom/doomweapons.txt b/wadsrc/static/actors/doom/doomweapons.txt
index 3abab7dbf..be3fa9e32 100644
--- a/wadsrc/static/actors/doom/doomweapons.txt
+++ b/wadsrc/static/actors/doom/doomweapons.txt
@@ -340,6 +340,45 @@ ACTOR Rocket
 	}
 }
 
+// --------------------------------------------------------------------------
+//
+// Grenade -- Taken and adapted from Skulltag
+//
+// --------------------------------------------------------------------------
+
+ACTOR Grenade
+{
+	SpawnID 216
+	Radius 8
+	Height 8
+	Speed 25
+	Damage 20
+	Projectile
+	-NOGRAVITY
+	+RANDOMIZE
+	+DEHEXPLOSION
+	+GRENADETRAIL
+	BounceType "Doom"
+	Gravity 0.25
+	SeeSound "weapons/grenlf"
+	DeathSound "weapons/grenlx"
+	BounceSound "weapons/grbnce"
+	Obituary "$OB_GRENADE"
+	DamageType Grenade
+
+	States
+	{
+	Spawn:
+		SGRN A 1 Bright 
+		Loop
+	Death:
+		MISL B 8 Bright A_Explode
+		MISL C 6 Bright
+		MISL D 4 Bright
+		Stop
+	}
+}
+
 // --------------------------------------------------------------------------
 //
 // Plasma rifle
diff --git a/wadsrc/static/actors/shared/inventory.txt b/wadsrc/static/actors/shared/inventory.txt
index 03285eea5..bd084813b 100644
--- a/wadsrc/static/actors/shared/inventory.txt
+++ b/wadsrc/static/actors/shared/inventory.txt
@@ -25,6 +25,7 @@ ACTOR Inventory native
 	action native A_LoadShotgun2();
 	action native A_CloseShotgun2();
 	action native A_FireCGun();
+	action native A_FireSTGrenade(class<Actor> grenadetype = "Grenade");
 	action native A_FireMissile();
 	action native A_FirePlasma();
 	action native A_FireRailgun();
diff --git a/wadsrc/static/sndinfo.txt b/wadsrc/static/sndinfo.txt
index 8a6764043..72912cbf2 100644
--- a/wadsrc/static/sndinfo.txt
+++ b/wadsrc/static/sndinfo.txt
@@ -201,6 +201,9 @@ weapons/plasmax			dsfirxpl
 weapons/bfgf			dsbfg
 weapons/bfgx			dsrxplod
 weapons/railgf			railgf1
+weapons/grbnce          dsbounce
+weapons/grenlx			dsgrnexp
+weapons/grenlf			dsglaunc
 
 // Problem: weapons/rocklx needs to be unlimited but
 // is also used for the MAP30 brain explosion.