diff --git a/menudef.txt b/menudef.txt
index fb5be4a..923d318 100644
--- a/menudef.txt
+++ b/menudef.txt
@@ -3,13 +3,14 @@ OptionValue "Nice_Modes" {
 	1, "Subtract"
 	2, "Compress"
 	3, "Clamp"
+	4, "Crush"
 	10, "DarkDoom Lite"
 	11, "DarkDoom Classic"
 	12, "DarkDoom Black"
 }
 
 OptionValue "Nice_Settings" {
-	//0, "Disable"
+	0, "Disable"
 	1, "Dim"
 	2, "Murky"
 	3, "Dismal"
diff --git a/zscript.zsc b/zscript.zsc
index f00ad30..a0f5284 100644
--- a/zscript.zsc
+++ b/zscript.zsc
@@ -67,7 +67,7 @@ class DarkDoomZ_SectorLightAdjust : EventHandler {
 				if(IsSky) FinalAdjustment *= (0.5 * SkyMode);
 
 				// Link to graphing calculator depiction of different modes
-				// https://www.desmos.com/calculator/iphz6pi8yj
+				// https://www.desmos.com/calculator/n1lvnyceve
 				switch(Mode) {
 					case 1: //subtract raw light level (simple fade)
 						Level.Sectors[i].Lightlevel = BaseLightLevels[i] - FinalAdjustment;
@@ -78,7 +78,9 @@ class DarkDoomZ_SectorLightAdjust : EventHandler {
 					case 3: //clamp max brightness level
 						Level.Sectors[i].Lightlevel = clamp(BaseLightLevels[i], 0, 256 - FinalAdjustment);
 						break;
-					case 4: //
+					case 4: //apply exponential gamma curve
+						Level.Sectors[i].Lightlevel = (256 - (FinalAdjustment ** (FinalAdjustment / 256))) * (BaseLightLevels[i] / 256.0) ** (1 + (FinalAdjustment / 32)) ;
+						break;
 					case 10: //DarkDoom Lite (fixed subtract mode)
 						Level.Sectors[i].Lightlevel = BaseLightLevels[i] - 96;
 						break;