diff --git a/assets/mods/basegame/blocks/blocks.csv b/assets/mods/basegame/blocks/blocks.csv
index 2c1ed4b57..2d1b77a92 100644
--- a/assets/mods/basegame/blocks/blocks.csv
+++ b/assets/mods/basegame/blocks/blocks.csv
@@ -156,6 +156,7 @@
 "4094";"N/A";"N/A";"ACTORBLOCK_NO_PASS_RIGHT";"0.0312";"0.0312";"0.0312";"0.0312";"1";"1";"NULL";"0";"0";"N/A";"0";"0";"4";"0.0";"0.0";"0.0";"0.0";"N/A";"N/A";"0.0";"INTERNAL,ACTORBLOCK,NORANDTILE"
 "4095";"N/A";"N/A";"ACTORBLOCK_NO_PASS_LEFT";"0.0312";"0.0312";"0.0312";"0.0312";"1";"1";"NULL";"0";"0";"N/A";"0";"0";"4";"0.0";"0.0";"0.0";"0.0";"N/A";"N/A";"0.0";"INTERNAL,ACTORBLOCK,NORANDTILE"
 "-1";"N/A";"N/A";"BLOCK_NULL";"4.0000";"4.0000";"4.0000";"4.0000";"-1";"2600";"NULL";"0";"1";"N/A";"0";"0";"16";"0.0000";"0.0000";"0.0000";"0.0000";"N/A";"N/A";"0.0";"INTERNAL,NORANDTILE"
+"-2";"N/A";"N/A";"BLOCK_NULL";"4.0000";"4.0000";"4.0000";"4.0000";"-1";"2600";"NULL";"1";"1";"N/A";"0";"0";"16";"0.0000";"0.0000";"0.0000";"0.0000";"N/A";"N/A";"0.0";"INTERNAL,NORANDTILE"
 
 
 ## Notes ##
diff --git a/src/net/torvald/terrarum/blockproperties/Block.kt b/src/net/torvald/terrarum/blockproperties/Block.kt
index e6992298d..1913e77a7 100644
--- a/src/net/torvald/terrarum/blockproperties/Block.kt
+++ b/src/net/torvald/terrarum/blockproperties/Block.kt
@@ -132,5 +132,6 @@ object Block {
     const val WATER = "basegame:4095"
 
     const val NULL = "basegame:-1"
+    const val NOT_GENERATED = "basegame:-2"
 
 }
diff --git a/src/net/torvald/terrarum/blockproperties/Fluid.kt b/src/net/torvald/terrarum/blockproperties/Fluid.kt
index bdb54f96d..2902c122e 100644
--- a/src/net/torvald/terrarum/blockproperties/Fluid.kt
+++ b/src/net/torvald/terrarum/blockproperties/Fluid.kt
@@ -12,5 +12,4 @@ object Fluid {
     val WATER = "fluid@basegame:1"
     val LAVA = "fluid@basegame:2"
 
-
 }
\ No newline at end of file
diff --git a/src/net/torvald/terrarum/gameworld/BlockLayerI16.kt b/src/net/torvald/terrarum/gameworld/BlockLayerI16.kt
index 48ce37817..cb4c5ae0c 100644
--- a/src/net/torvald/terrarum/gameworld/BlockLayerI16.kt
+++ b/src/net/torvald/terrarum/gameworld/BlockLayerI16.kt
@@ -30,7 +30,7 @@ open class BlockLayerI16(override val width: Int, override val height: Int) : Bl
         get() = ptr.destroyed
 
     init {
-        ptr.fillWith(0)
+        ptr.fillWith(-1)
     }
 
     /**
diff --git a/src/net/torvald/terrarum/gameworld/BlockLayerI16F16.kt b/src/net/torvald/terrarum/gameworld/BlockLayerI16F16.kt
index b6ea9808c..626cd1bfe 100644
--- a/src/net/torvald/terrarum/gameworld/BlockLayerI16F16.kt
+++ b/src/net/torvald/terrarum/gameworld/BlockLayerI16F16.kt
@@ -29,7 +29,7 @@ class BlockLayerI16F16(override val width: Int, override val height: Int) : Bloc
         get() = ptr.destroyed
 
     init {
-        ptr.fillWith(0)
+        ptr.fillWith(-1)
     }
 
     /**
diff --git a/src/net/torvald/terrarum/gameworld/BlockLayerI16I8.kt b/src/net/torvald/terrarum/gameworld/BlockLayerOresI16I8.kt
similarity index 96%
rename from src/net/torvald/terrarum/gameworld/BlockLayerI16I8.kt
rename to src/net/torvald/terrarum/gameworld/BlockLayerOresI16I8.kt
index cccac305f..3163aa386 100644
--- a/src/net/torvald/terrarum/gameworld/BlockLayerI16I8.kt
+++ b/src/net/torvald/terrarum/gameworld/BlockLayerOresI16I8.kt
@@ -13,7 +13,7 @@ import net.torvald.unsafe.UnsafePtr
  * where a_n is a tile number, p_n is a placement index
  * Created by minjaesong on 2023-10-10.
  */
-class BlockLayerI16I8 (override val width: Int, override val height: Int) : BlockLayer {
+class BlockLayerOresI16I8 (override val width: Int, override val height: Int) : BlockLayer {
     override val bytesPerBlock = BYTES_PER_BLOCK
 
     // for some reason, all the efforts of saving the memory space were futile.
@@ -25,7 +25,7 @@ class BlockLayerI16I8 (override val width: Int, override val height: Int) : Bloc
         get() = ptr.destroyed
 
     init {
-        ptr.fillWith(0)
+        ptr.fillWith(0) // there is no NOT-GENERATED for ores, keep it as 0
     }
 
     /**
diff --git a/src/net/torvald/terrarum/gameworld/GameWorld.kt b/src/net/torvald/terrarum/gameworld/GameWorld.kt
index c47e8240c..9ba235302 100644
--- a/src/net/torvald/terrarum/gameworld/GameWorld.kt
+++ b/src/net/torvald/terrarum/gameworld/GameWorld.kt
@@ -86,7 +86,7 @@ open class GameWorld(
     //layers
     @Transient open lateinit var layerWall: BlockLayerI16
     @Transient open lateinit var layerTerrain: BlockLayerI16
-    @Transient open lateinit var layerOres: BlockLayerI16I8 // damage to the block follows `terrainDamages`
+    @Transient open lateinit var layerOres: BlockLayerOresI16I8 // damage to the block follows `terrainDamages`
     @Transient open lateinit var layerFluids: BlockLayerI16F16
     val wallDamages = HashArray<Float>()
     val terrainDamages = HashArray<Float>()
@@ -146,22 +146,25 @@ open class GameWorld(
     )
 
     @Transient private val forcedTileNumberToNames = hashSetOf(
-        Block.AIR, Block.UPDATE
+        Block.AIR, Block.UPDATE, Block.NOT_GENERATED
     )
     @Transient private val forcedFluidNumberToTiles = hashSetOf(
         Fluid.NULL
     )
     val tileNumberToNameMap = HashArray<ItemID>().also {
         it[0] = Block.AIR
-        it[2] = Block.UPDATE
+        it[1] = Block.UPDATE
+        it[65535] = Block.NOT_GENERATED // unlike Block.NULL, this one is solid
     }
     val fluidNumberToNameMap = HashArray<ItemID>().also {
         it[0] = Fluid.NULL
+        it[65535] = Fluid.NULL // 65535 denotes "not generated"
     }
     // does not go to the savefile
     @Transient val tileNameToNumberMap = HashMap<ItemID, Int>().also {
         it[Block.AIR] = 0
-        it[Block.UPDATE] = 2
+        it[Block.UPDATE] = 1
+        it[Block.NOT_GENERATED] = 65535 // unlike Block.NULL, this one is solid
     }
     @Transient val fluidNameToNumberMap = HashMap<ItemID, Int>().also {
         it[Fluid.NULL] = 0
@@ -221,7 +224,7 @@ open class GameWorld(
 
         layerTerrain = BlockLayerI16(width, height)
         layerWall = BlockLayerI16(width, height)
-        layerOres = BlockLayerI16I8(width, height)
+        layerOres = BlockLayerOresI16I8(width, height)
         layerFluids = BlockLayerI16F16(width, height)
         chunkFlags = Array(height / CHUNK_H) { ByteArray(width / CHUNK_W) }
 
@@ -252,8 +255,13 @@ open class GameWorld(
     fun coordInWorldStrict(x: Int, y: Int) = x in 0 until width && y in 0 until height // ROUNDWORLD implementation
 
     fun renumberTilesAfterLoad() {
+        // patch the "old"map
+        tileNumberToNameMap[0] = Block.AIR
+        tileNumberToNameMap[1] = Block.UPDATE
+        tileNumberToNameMap[65535] = Block.NOT_GENERATED
         // before the renaming, update the name maps
         val oldTileNumberToNameMap: Map<Long, ItemID> = tileNumberToNameMap.toMap()
+
         tileNumberToNameMap.clear()
         tileNameToNumberMap.clear()
         App.tileMaker.tags.forEach {
@@ -263,24 +271,29 @@ open class GameWorld(
             tileNameToNumberMap[it.key] = it.value.tileNumber
         }
 
+        // force this rule to the old saves
+        tileNumberToNameMap[0] = Block.AIR
+        tileNumberToNameMap[1] = Block.UPDATE
+        tileNumberToNameMap[65535] = Block.NOT_GENERATED
+        tileNameToNumberMap[Block.AIR] = 0
+        tileNameToNumberMap[Block.UPDATE] = 1
+        tileNameToNumberMap[Block.NOT_GENERATED] = 65535
+        fluidNumberToNameMap[0] = Fluid.NULL
+        fluidNumberToNameMap[65535] = Fluid.NULL
+        fluidNameToNumberMap[Fluid.NULL] = 0
+
         // perform renaming of tile layers
         for (y in 0 until layerTerrain.height) {
             for (x in 0 until layerTerrain.width) {
                 layerTerrain.unsafeSetTile(x, y, tileNameToNumberMap[oldTileNumberToNameMap[layerTerrain.unsafeGetTile(x, y).toLong()]]!!)
                 layerWall.unsafeSetTile(x, y, tileNameToNumberMap[oldTileNumberToNameMap[layerWall.unsafeGetTile(x, y).toLong()]]!!)
-                layerOres.unsafeSetTileKeepPlacement(x, y, tileNameToNumberMap[oldTileNumberToNameMap[layerOres.unsafeGetTile(x, y).toLong()]]!!)
+
+                val oldNum = layerOres.unsafeGetTile(x, y).toLong()
+                val oldName = oldTileNumberToNameMap[oldNum]
+                layerOres.unsafeSetTileKeepPlacement(x, y, oldName.let { tileNameToNumberMap[it] ?: throw NullPointerException("Unknown tile name: $oldName (<- $oldNum)") })
             }
         }
 
-        // force this rule to the old saves
-        tileNumberToNameMap[0] = Block.AIR
-        tileNumberToNameMap[2] = Block.UPDATE
-        tileNameToNumberMap[Block.AIR] = 0
-        tileNameToNumberMap[Block.UPDATE] = 2
-        fluidNumberToNameMap[0] = Fluid.NULL
-        fluidNameToNumberMap[Fluid.NULL] = 0
-
-
         BlocksDrawer.rebuildInternalPrecalculations()
     }
     
diff --git a/src/net/torvald/terrarum/modulebasegame/console/ExportMap.kt b/src/net/torvald/terrarum/modulebasegame/console/ExportMap.kt
index 85832ac7c..1ef3e4f5d 100644
--- a/src/net/torvald/terrarum/modulebasegame/console/ExportMap.kt
+++ b/src/net/torvald/terrarum/modulebasegame/console/ExportMap.kt
@@ -53,6 +53,9 @@ internal object ExportMap : ConsoleCommand {
             var mapDataPointer = 0
 
             for ((terr, wall, ore) in world.terrainIterator()) {
+                val terr = if (terr == "basegame:-2") "basegame:-1" else terr
+                val wall = if (wall == "basegame:-2") "basegame:-1" else wall // world.getTileFromWall() returns item ID WITHOUT wall tag
+
                 val colOre = (oreColourMap.get(ore) ?: throw NullPointerException("nullore $ore")).toByteArray()
                 val colFore = (App.tileMaker.terrainTileColourMap.get(terr) ?: throw NullPointerException("nullterr $terr")).toByteArray()
                 val colWall = (App.tileMaker.terrainTileColourMap.get(wall) ?: throw NullPointerException("nullwall $wall")).cpy().mul(WALL_OVERLAY).toByteArray()
diff --git a/src/net/torvald/terrarum/modulebasegame/serialise/WriteSavegame.kt b/src/net/torvald/terrarum/modulebasegame/serialise/WriteSavegame.kt
index 792a9ce95..a56bc8ae3 100644
--- a/src/net/torvald/terrarum/modulebasegame/serialise/WriteSavegame.kt
+++ b/src/net/torvald/terrarum/modulebasegame/serialise/WriteSavegame.kt
@@ -6,7 +6,7 @@ import net.torvald.terrarum.App.printdbg
 import net.torvald.terrarum.console.Echo
 import net.torvald.terrarum.gameworld.BlockLayerI16
 import net.torvald.terrarum.gameworld.BlockLayerI16F16
-import net.torvald.terrarum.gameworld.BlockLayerI16I8
+import net.torvald.terrarum.gameworld.BlockLayerOresI16I8
 import net.torvald.terrarum.gameworld.GameWorld
 import net.torvald.terrarum.gameworld.GameWorld.Companion.CHUNK_LOADED
 import net.torvald.terrarum.langpack.Lang
@@ -150,7 +150,7 @@ object LoadSavegame {
 
         world.layerTerrain = BlockLayerI16(world.width, world.height)
         world.layerWall = BlockLayerI16(world.width, world.height)
-        world.layerOres = BlockLayerI16I8(world.width, world.height)
+        world.layerOres = BlockLayerOresI16I8(world.width, world.height)
         world.layerFluids = BlockLayerI16F16(world.width, world.height)
         world.chunkFlags = Array(world.height / LandUtil.CHUNK_H) { ByteArray(world.width / LandUtil.CHUNK_W) }
 
diff --git a/src/net/torvald/terrarum/modulebasegame/serialise/WriteWorld.kt b/src/net/torvald/terrarum/modulebasegame/serialise/WriteWorld.kt
index 13952953a..61039b979 100644
--- a/src/net/torvald/terrarum/modulebasegame/serialise/WriteWorld.kt
+++ b/src/net/torvald/terrarum/modulebasegame/serialise/WriteWorld.kt
@@ -4,8 +4,6 @@ import net.torvald.terrarum.ItemCodex
 import net.torvald.terrarum.gameactors.Actor
 import net.torvald.terrarum.gameactors.NoSerialise
 import net.torvald.terrarum.gameworld.BlockLayer
-import net.torvald.terrarum.gameworld.BlockLayerI16
-import net.torvald.terrarum.gameworld.BlockLayerI16I8
 import net.torvald.terrarum.gameworld.GameWorld
 import net.torvald.terrarum.modulebasegame.TerrarumIngame
 import net.torvald.terrarum.modulebasegame.gameactors.IngamePlayer
@@ -14,7 +12,6 @@ import net.torvald.terrarum.realestate.LandUtil
 import net.torvald.terrarum.savegame.ByteArray64
 import net.torvald.terrarum.savegame.ByteArray64Writer
 import net.torvald.terrarum.serialise.Common
-import net.torvald.terrarum.serialise.toUint
 import net.torvald.terrarum.utils.PlayerLastStatus
 import net.torvald.terrarum.weather.WeatherMixer
 import java.io.File
diff --git a/src/net/torvald/terrarum/serialise/PointOfInterest.kt b/src/net/torvald/terrarum/serialise/PointOfInterest.kt
index a7e5e2afd..928091583 100644
--- a/src/net/torvald/terrarum/serialise/PointOfInterest.kt
+++ b/src/net/torvald/terrarum/serialise/PointOfInterest.kt
@@ -2,7 +2,6 @@ package net.torvald.terrarum.serialise
 
 import com.badlogic.gdx.utils.Json
 import com.badlogic.gdx.utils.JsonValue
-import net.torvald.terrarum.App.printdbg
 import net.torvald.terrarum.TerrarumAppConfiguration
 import net.torvald.terrarum.blockproperties.Block
 import net.torvald.terrarum.gameitems.ItemID
diff --git a/src/net/torvald/terrarum/serialise/ReadSimpleWorld.kt b/src/net/torvald/terrarum/serialise/ReadSimpleWorld.kt
index e68281703..91e527095 100644
--- a/src/net/torvald/terrarum/serialise/ReadSimpleWorld.kt
+++ b/src/net/torvald/terrarum/serialise/ReadSimpleWorld.kt
@@ -5,7 +5,7 @@ import net.torvald.terrarum.IngameInstance
 import net.torvald.terrarum.ItemCodex
 import net.torvald.terrarum.gameactors.Actor
 import net.torvald.terrarum.gameworld.BlockLayerI16F16
-import net.torvald.terrarum.gameworld.BlockLayerI16I8
+import net.torvald.terrarum.gameworld.BlockLayerOresI16I8
 import net.torvald.terrarum.gameworld.GameWorld
 import net.torvald.terrarum.gameworld.SimpleGameWorld
 import java.io.File
@@ -25,7 +25,7 @@ object ReadSimpleWorld {
         world.tileNumberToNameMap.forEach { l, s ->
             world.tileNameToNumberMap[s] = l.toInt()
         }
-        world.layerOres = BlockLayerI16I8(world.width, world.height)
+        world.layerOres = BlockLayerOresI16I8(world.width, world.height)
         world.layerFluids = BlockLayerI16F16(world.width, world.height)
 
         ItemCodex.loadFromSave(origin, world.dynamicToStaticTable, world.dynamicItemInventory)
diff --git a/src/net/torvald/terrarum/worlddrawer/CreateTileAtlas.kt b/src/net/torvald/terrarum/worlddrawer/CreateTileAtlas.kt
index e7361d086..26fab011b 100644
--- a/src/net/torvald/terrarum/worlddrawer/CreateTileAtlas.kt
+++ b/src/net/torvald/terrarum/worlddrawer/CreateTileAtlas.kt
@@ -11,6 +11,7 @@ import net.torvald.gdx.graphics.Cvec
 import net.torvald.terrarum.*
 import net.torvald.terrarum.App.printdbg
 import net.torvald.terrarum.TerrarumAppConfiguration.TILE_SIZE
+import net.torvald.terrarum.blockproperties.Block
 import net.torvald.terrarum.gameitems.ItemID
 import net.torvald.terrarum.utils.HashArray
 import net.torvald.terrarum.worlddrawer.CreateTileAtlas.AtlasSource.*
@@ -310,6 +311,9 @@ class CreateTileAtlas {
             )
         }
 
+        // special colour
+        terrainTileColourMap[Block.NULL] = Cvec(1f, 0f, 0f, 1f)
+
         itemTerrainTexture = Texture(itemTerrainPixmap)
         itemTerrainTextureGlow = Texture(itemTerrainPixmapGlow)
         itemTerrainTextureEmissive = Texture(itemTerrainPixmapEmissive)