diff --git a/extras/conf/udb/Includes/SRB222_linedefs.cfg b/extras/conf/udb/Includes/SRB222_linedefs.cfg
index 99ec6ec79..54ddd17bb 100644
--- a/extras/conf/udb/Includes/SRB222_linedefs.cfg
+++ b/extras/conf/udb/Includes/SRB222_linedefs.cfg
@@ -1917,6 +1917,54 @@ udmf
 			}
 		}
 
+		259
+		{
+			title = "Custom";
+			prefix = "(259)";
+			arg0
+			{
+				title = "Target sector tag";
+				type = 13;
+			}
+			arg1
+			{
+				title = "Flags";
+				type = 12;
+				enum
+				{
+					1 = "Exists";
+					2 = "Block player";
+					4 = "Block others";
+					8 = "Render sides";
+					16 = "Render planes";
+					32 = "Water";
+					64 = "No shadow";
+					128 = "Cut solid walls";
+					256 = "Cut extra walls";
+					512 = "Split sprites";
+					1024 = "Render inside planes";
+					2048 = "Extra";
+					4096 = "Translucent";
+					8192 = "Fog";
+					16384 = "Only render inside planes";
+					32768 = "Render inside walls";
+					65536 = "Only render inside walls";
+					131072 = "Double shadow";
+					262144 = "Water bobbing";
+					524288 = "Don't respawn";
+					1048576 = "Crumbling";
+					2097152 = "Goo water";
+					4194304 = "Mario block";
+					8388608 = "Bustable";
+					16777216 = "Quicksand";
+					33554432 = "Intangible from below";
+					67108864 = "Intangible from above";
+					1073741824 = "Ripple effect";
+					2147483648 = "Don't copy light level";
+				}
+			}
+		}
+
 		260
 		{
 			title = "Add Raise Thinker";
diff --git a/src/p_setup.c b/src/p_setup.c
index a3876888b..2b47464ff 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -3157,6 +3157,20 @@ static void P_ConvertBinaryMap(void)
 			if (lines[i].flags & ML_EFFECT1)
 				lines[i].args[1] = 1;
 			break;
+		case 259: //Custom FOF
+			if (lines[i].sidenum[1] == 0xffff)
+				I_Error("Custom FOF (tag %d) found without a linedef back side!", lines[i].tag);
+
+			lines[i].args[0] = lines[i].tag;
+			lines[i].args[1] = sides[lines[i].sidenum[1]].toptexture;
+			if (lines[i].args[1] & FF_TRANSLUCENT)
+			{
+				if (sides[lines[i].sidenum[0]].toptexture > 0)
+					lines[i].alpha = (sides[lines[i].sidenum[0]].toptexture << FRACBITS)/255;
+				else
+					lines[i].alpha = FRACUNIT/2;
+			}
+			break;
 		case 443: //Call Lua function
 			if (lines[i].text)
 			{
diff --git a/src/p_spec.c b/src/p_spec.c
index a324e5a15..6040ac6eb 100644
--- a/src/p_spec.c
+++ b/src/p_spec.c
@@ -6947,7 +6947,7 @@ void P_SpawnSpecials(boolean fromnetsave)
 				{
 					ffloor_t *fflr = P_AddFakeFloor(&sectors[s], lines[i].frontsector, lines + i, ffloorflags, secthinkers);
 					fflr->sinkspeed = abs(lines[i].args[2]) << (FRACBITS - 1);
-					fflr->fricttion = abs(lines[i].args[3]) << (FRACBITS - 6);
+					fflr->friction = abs(lines[i].args[3]) << (FRACBITS - 6);
 				}
 				break;
 
@@ -6957,13 +6957,39 @@ void P_SpawnSpecials(boolean fromnetsave)
 				break;
 
 			case 259: // Custom FOF
-				if (lines[i].sidenum[1] != 0xffff)
+				for (s = -1; (s = P_FindSectorFromTag(lines[i].args[0], s)) >= 0 ;)
 				{
-					ffloortype_e fofflags = sides[lines[i].sidenum[1]].toptexture;
-					P_AddFakeFloorsByLine(i, fofflags, secthinkers);
+					ffloor_t *fflr = P_AddFakeFloor(&sectors[s], lines[i].frontsector, lines + i, lines[i].args[1], secthinkers);
+					if (!udmf) // Ugly backwards compatibility stuff
+					{
+						if (lines[i].args[1] & FF_QUICKSAND)
+						{
+							fflr->sinkspeed = abs(lines[i].dx) >> 1;
+							fflr->friction = abs(lines[i].dy) >> 6;
+						}
+						if (lines[i].args[1] & FF_BUSTUP)
+						{
+							if (lines[i].args[1] & BFF_SHATTER)
+								fflr->busttype = BT_TOUCH;
+							else if (lines[i].args[1] & BFF_SPINBUST)
+								fflr->busttype = BT_SPIN;
+							else if (lines[i].args[1] & BFF_STRONGBUST)
+								fflr->busttype = BT_STRONG;
+							else
+								fflr->busttype = BT_REGULAR;
+
+							if (lines[i].args[1] & BFF_SHATTERBOTTOM)
+								fflr->bustflags |= BF_ONLYBOTTOM;
+							if (lines[i].flags & ML_EFFECT4)
+								fflr->bustflags |= BF_PUSHABLES;
+							if (lines[i].flags & ML_EFFECT5)
+							{
+								fflr->bustflags |= BF_EXECUTOR;
+								fflr->busttag = P_AproxDistance(lines[i].dx, lines[i].dy) >> FRACBITS;
+							}
+						}
+					}
 				}
-				else
-					I_Error("Custom FOF (tag %d) found without a linedef back side!", lines[i].tag);
 				break;
 
 			case 260: // Add raise thinker to FOF
@@ -7326,6 +7352,7 @@ void P_SpawnSpecials(boolean fromnetsave)
 								continue;
 
 							rover->flags |= FF_BUSTUP;
+							rover->spawnflags |= FF_BUSTUP;
 							rover->busttype = busttype;
 							rover->bustflags = bustflags;
 							rover->busttag = lines[i].args[3];
@@ -7336,9 +7363,44 @@ void P_SpawnSpecials(boolean fromnetsave)
 				}
 				break;
 			}
+
+			case 265: // Make FOF quicksand
+			{
+				if (!udmf)
+					break;
+
+				for (l = -1; (l = P_FindLineFromTag(lines[i].args[0], l)) >= 0 ;)
+				{
+					if (lines[l].special < 100 || lines[l].special >= 300)
+						continue;
+
+					for (s = -1; (s = P_FindSectorFromTag(lines[l].args[0], s)) >= 0 ;)
+					{
+						ffloor_t *rover;
+
+						for (rover = sectors[s].ffloors; rover; rover = rover->next)
+						{
+							if (rover->master != lines + l)
+								continue;
+
+							rover->flags |= FF_QUICKSAND;
+							rover->spawnflags |= FF_QUICKSAND;
+							rover->sinkspeed = abs(lines[i].args[1]) << (FRACBITS - 1);
+							rover->friction = abs(lines[i].args[2]) << (FRACBITS - 6);
+							CheckForQuicksand = true;
+							break;
+						}
+					}
+				}
+				break;
+			}
 		}
 	}
 
+
+
+
+
 	// Allocate each list
 	for (i = 0; i < numsectors; i++)
 		if(secthinkers[i].thinkers)
diff --git a/src/r_defs.h b/src/r_defs.h
index 508b1f062..c791117ba 100644
--- a/src/r_defs.h
+++ b/src/r_defs.h
@@ -148,6 +148,12 @@ typedef enum
 	FF_COLORMAPONLY      = 0x80000000, ///< Only copy the colormap, not the lightlevel
 } ffloortype_e;
 
+//Binary map format ffloor flags, for backwards compatibility only
+#define BFF_SHATTERBOTTOM 0x200000
+#define BFF_SHATTER       0x8000000
+#define BFF_SPINBUST      0x10000000
+#define BFF_STRONGBUST    0x20000000
+
 typedef enum
 {
 	BT_TOUCH,