diff --git a/src/shaders/screenWorld.frag b/src/shaders/screenWorld.frag
index 7657b96..f61da39 100644
--- a/src/shaders/screenWorld.frag
+++ b/src/shaders/screenWorld.frag
@@ -8,6 +8,12 @@ out vec4 FragColor;
 uniform sampler2D map;
 uniform sampler2D uMaterialColors;
 
+float hash(ivec2 p) {
+    int h = p.x * 374761393 + p.y * 668265263;
+    h = (h ^ (h >> 13)) * 1274126177;
+    return float(h & 0x7fffffff) / float(0x7fffffff);
+}
+
 void main()	{
     vec4 value = texture(map, vUv);
 
@@ -30,7 +36,10 @@ void main()	{
     // non-air cells use material color as base, with pheromone tint
     if (materialId != MAT_AIR) {
         vec4 matColor = texelFetch(uMaterialColors, ivec2(materialId, 0), 0);
-        color = mix(matColor.rgb, t, a * 0.3);
+        // per-pixel color variation: +/-4% brightness noise
+        float colorNoise = hash(ivec2(gl_FragCoord.xy)) * 0.08 - 0.04;
+        vec3 variedColor = matColor.rgb + colorNoise;
+        color = mix(variedColor, t, a * 0.3);
     }
 
     FragColor = vec4(color, 1);