ThickFogDistance and ThickFogMultiplier MAPINFO variables adds thicker fog (Vulkan and OpenGL only) beyond ThickFogDistance, as long as it is possible. But default it is -1.f (disabled).

src/g_dumpinfo.cpp

@@ -430,6 +430,7 @@ CCMD(skyfog)
 		// Do this only on the primary level.
 		primaryLevel->skyfog = max(0, (int)strtoull(argv[1], NULL, 0));
 	}
+	Printf("%d\n", primaryLevel->skyfog);
 }