diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/tile/BuiltinMetaMaterials.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/tile/BuiltinMetaMaterials.kt
index 67f38429..288498e6 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/tile/BuiltinMetaMaterials.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/tile/BuiltinMetaMaterials.kt
@@ -24,7 +24,7 @@ val Registry.Ref<TileDefinition>.isObjectPlatformTile: Boolean
 	get() = entry == BuiltinMetaMaterials.OBJECT_PLATFORM
 
 val Registry.Entry<TileDefinition>.isEmptyTile: Boolean
-	get() = this == BuiltinMetaMaterials.EMPTY
+	get() = this == BuiltinMetaMaterials.EMPTY || this == BuiltinMetaMaterials.NULL
 
 val Registry.Entry<TileDefinition>.isNullTile: Boolean
 	get() = this == BuiltinMetaMaterials.NULL
@@ -52,6 +52,21 @@ val Registry.Entry<LiquidDefinition>.isEmptyLiquid: Boolean
 val Registry.Ref<LiquidDefinition>.isEmptyLiquid: Boolean
 	get() = entry == null || entry == BuiltinMetaMaterials.NO_LIQUID
 
+// these are hardcoded way harder than any Hard-Coder:tm:
+// considering there is no way you gonna mod-in this many (16 bit uint) dungeons
+const val NO_DUNGEON_ID = 65535
+const val SPAWN_DUNGEON_ID = 65534
+const val MICRO_DUNGEON_ID = 65533
+// meta dungeon signalling player built structures
+const val ARTIFICIAL_DUNGEON_ID = 65532
+// indicates a block that has been destroyed
+const val DESTROYED_BLOCK_ID = 65531
+// dungeonId for zero-g areas with and without tile protection
+const val ZERO_GRAVITY_DUNGEON_ID = 65525
+const val PROTECTED_ZERO_GRAVITY_DUNGEON_ID = 65524
+
+const val FIRST_RESERVED_DUNGEON_ID = 65520
+
 object BuiltinMetaMaterials {
 	private fun make(id: Int, name: String, collisionType: CollisionType) = Registries.tiles.add(name, id, TileDefinition(
 		materialId = id,
@@ -117,7 +132,7 @@ object BuiltinMetaMaterials {
 		OBJECT_PLATFORM,
 	)
 
-	val EMPTY_MOD = makeMod(65535, "empty")
+	val EMPTY_MOD = makeMod(65535, "none")
 	val BIOME_MOD = makeMod(65534, "biome")
 	val UNDERGROUND_BIOME_MOD = makeMod(65533, "underground_biome")
 
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/WorldTemplate.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/WorldTemplate.kt
index fe35f891..31e0f76f 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/WorldTemplate.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/WorldTemplate.kt
@@ -1,32 +1,27 @@
 package ru.dbotthepony.kstarbound.defs.world
 
+import com.github.benmanes.caffeine.cache.Caffeine
+import com.github.benmanes.caffeine.cache.Scheduler
 import com.google.gson.JsonObject
-import ru.dbotthepony.kommons.arrays.Object2DArray
-import ru.dbotthepony.kommons.util.AABB
 import ru.dbotthepony.kommons.util.AABBi
 import ru.dbotthepony.kommons.util.Either
 import ru.dbotthepony.kommons.vector.Vector2d
 import ru.dbotthepony.kommons.vector.Vector2i
 import ru.dbotthepony.kstarbound.Globals
-import ru.dbotthepony.kstarbound.Registries
 import ru.dbotthepony.kstarbound.Registry
 import ru.dbotthepony.kstarbound.Starbound
 import ru.dbotthepony.kstarbound.defs.tile.BuiltinMetaMaterials
 import ru.dbotthepony.kstarbound.defs.tile.LiquidDefinition
 import ru.dbotthepony.kstarbound.defs.tile.TileDefinition
 import ru.dbotthepony.kstarbound.defs.tile.TileModifierDefinition
-import ru.dbotthepony.kstarbound.defs.tile.isEmptyTile
-import ru.dbotthepony.kstarbound.defs.tile.isNullTile
-import ru.dbotthepony.kstarbound.defs.tile.supportsModifier
 import ru.dbotthepony.kstarbound.json.builder.JsonFactory
 import ru.dbotthepony.kstarbound.math.quintic2
 import ru.dbotthepony.kstarbound.util.random.random
 import ru.dbotthepony.kstarbound.world.Universe
 import ru.dbotthepony.kstarbound.world.UniversePos
 import ru.dbotthepony.kstarbound.world.WorldGeometry
-import ru.dbotthepony.kstarbound.world.api.ImmutableCell
-import ru.dbotthepony.kstarbound.world.api.TileColor
 import ru.dbotthepony.kstarbound.world.physics.Poly
+import java.time.Duration
 import java.util.random.RandomGenerator
 
 class WorldTemplate(val geometry: WorldGeometry) {
@@ -156,6 +151,38 @@ class WorldTemplate(val geometry: WorldGeometry) {
 		return geometry.size.y / 2
 	}
 
+	data class PotentialBiomeItems(
+		// Potential items that would spawn at the given block assuming it is at
+		val surfaceBiomeItems: List<BiomePlaceables.DistributionItem>,
+
+		// ... Or on a cave surface.
+		val caveSurfaceBiomeItems: List<BiomePlaceables.DistributionItem>,
+
+		// ... Or on a cave ceiling.
+		val caveCeilingBiomeItems: List<BiomePlaceables.DistributionItem>,
+
+		// ... Or on a cave background wall.
+		val caveBackgroundBiomeItems: List<BiomePlaceables.DistributionItem>,
+
+		// ... Or in the ocean
+		val oceanItems: List<BiomePlaceables.DistributionItem>,
+	)
+
+	fun potentialBiomeItemsAt(x: Int, y: Int): PotentialBiomeItems {
+		val thisBlockBiome = cellInfo(geometry.x.cell(x), geometry.y.cell(y)).blockBiome
+		val lowerBlockBiome = cellInfo(geometry.x.cell(x), geometry.y.cell(y - 1)).blockBiome
+		val upperBlockBiome = cellInfo(geometry.x.cell(x), geometry.y.cell(y + 1)).blockBiome
+
+		return PotentialBiomeItems(
+			surfaceBiomeItems = lowerBlockBiome?.surfacePlaceables?.itemDistributions?.filter { it.mode == BiomePlaceablesDefinition.Placement.FLOOR } ?: listOf(),
+			oceanItems = thisBlockBiome?.surfacePlaceables?.itemDistributions?.filter { it.mode == BiomePlaceablesDefinition.Placement.OCEAN } ?: listOf(),
+
+			caveSurfaceBiomeItems = lowerBlockBiome?.undergroundPlaceables?.itemDistributions?.filter { it.mode == BiomePlaceablesDefinition.Placement.FLOOR } ?: listOf(),
+			caveCeilingBiomeItems = upperBlockBiome?.undergroundPlaceables?.itemDistributions?.filter { it.mode == BiomePlaceablesDefinition.Placement.CEILING } ?: listOf(),
+			caveBackgroundBiomeItems = thisBlockBiome?.undergroundPlaceables?.itemDistributions?.filter { it.mode == BiomePlaceablesDefinition.Placement.BACKGROUND } ?: listOf(),
+		)
+	}
+
 	class CellInfo(val x: Int, val y: Int) {
 		var foreground: Registry.Ref<TileDefinition> = BuiltinMetaMaterials.EMPTY.ref
 		var foregroundMod: Registry.Ref<TileModifierDefinition> = BuiltinMetaMaterials.EMPTY_MOD.ref
@@ -177,7 +204,18 @@ class WorldTemplate(val geometry: WorldGeometry) {
 		var backgroundCave = false
 	}
 
+	private val cellCache = Caffeine.newBuilder()
+		.maximumSize(125_000L)
+		.expireAfterAccess(Duration.ofMinutes(2))
+		.executor(Starbound.EXECUTOR)
+		.scheduler(Scheduler.systemScheduler())
+		.build<Vector2i, CellInfo> { (x, y) -> cellInfo0(x, y) }
+
 	fun cellInfo(x: Int, y: Int): CellInfo {
+		return cellCache.get(Vector2i(x, y))
+	}
+
+	private fun cellInfo0(x: Int, y: Int): CellInfo {
 		val info = CellInfo(x, y)
 		val layout = worldLayout ?: return info
 
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/server/ServerConnection.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/server/ServerConnection.kt
index ab37d10d..77c76549 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/server/ServerConnection.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/server/ServerConnection.kt
@@ -54,7 +54,7 @@ class ServerConnection(val server: StarboundServer, type: ConnectionType) : Conn
 	// packets which interact with world must be
 	// executed on world's thread
 	fun enqueue(task: ServerWorld.() -> Unit) {
-		return tracker?.enqueue(task) ?: throw IllegalStateException("Not in world.")
+		return tracker?.enqueue(task) ?: LOGGER.warn("$this tried to interact with world, but they are not in one.")
 	}
 
 	lateinit var shipWorld: ServerWorld
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerChunk.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerChunk.kt
index 70638958..1f9b11d1 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerChunk.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerChunk.kt
@@ -4,6 +4,8 @@ import it.unimi.dsi.fastutil.objects.ObjectAVLTreeSet
 import it.unimi.dsi.fastutil.objects.ObjectArrayList
 import it.unimi.dsi.fastutil.objects.ObjectArraySet
 import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.future.await
 import kotlinx.coroutines.launch
 import org.apache.logging.log4j.LogManager
@@ -12,6 +14,7 @@ import ru.dbotthepony.kommons.vector.Vector2d
 import ru.dbotthepony.kommons.vector.Vector2i
 import ru.dbotthepony.kstarbound.Starbound
 import ru.dbotthepony.kstarbound.defs.tile.BuiltinMetaMaterials
+import ru.dbotthepony.kstarbound.defs.tile.NO_DUNGEON_ID
 import ru.dbotthepony.kstarbound.defs.tile.TileDamage
 import ru.dbotthepony.kstarbound.defs.tile.TileDamageResult
 import ru.dbotthepony.kstarbound.defs.tile.TileDamageType
@@ -20,6 +23,7 @@ import ru.dbotthepony.kstarbound.defs.tile.isNullTile
 import ru.dbotthepony.kstarbound.defs.tile.supportsModifier
 import ru.dbotthepony.kstarbound.network.LegacyNetworkCellState
 import ru.dbotthepony.kstarbound.network.packets.clientbound.TileDamageUpdatePacket
+import ru.dbotthepony.kstarbound.util.random.staticRandomDouble
 import ru.dbotthepony.kstarbound.world.CHUNK_SIZE
 import ru.dbotthepony.kstarbound.world.Chunk
 import ru.dbotthepony.kstarbound.world.ChunkPos
@@ -33,6 +37,7 @@ import java.util.concurrent.CompletableFuture
 import java.util.concurrent.locks.ReentrantLock
 import java.util.function.Predicate
 import kotlin.concurrent.withLock
+import kotlin.coroutines.cancellation.CancellationException
 
 class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, ServerChunk>(world, pos) {
 	/**
@@ -46,9 +51,6 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 		TILES,
 		MICRO_DUNGEONS,
 		CAVE_LIQUID,
-		TILE_ENTITIES,
-		ENTITIES,
-
 		FULL; // indicates everything has been loaded
 	}
 
@@ -81,9 +83,44 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 			while (state < targetState) {
 				isBusy = true
 
-				val nextState = ServerChunk.State.entries[state.ordinal + 1]
+				val nextState = State.entries[state.ordinal + 1]
 
 				try {
+					if (nextState >= State.MICRO_DUNGEONS) {
+						val neighbours = ArrayList<ITicket>()
+
+						try {
+							// wait for neighbouring chunks to be as generated as our current state
+							// before we advance to next stage
+							// Yes, this will create quite big loading rectangle around
+							// players and other watching entities, but this is required
+							// to avoid generation artifacts, where this chunk tries to read
+							// from not sufficiently generated neighbours
+
+							for (neighbour in pos.neighbours()) {
+								val ticket = world.permanentChunkTicket(neighbour, state) ?: continue
+								neighbours.add(ticket)
+							}
+
+							for (neighbour in neighbours) {
+								var i = 0
+
+								while (!neighbour.chunk.isDone && ++i < 20) {
+									delay(500L)
+								}
+
+								if (!neighbour.chunk.isDone) {
+									LOGGER.error("Giving up waiting on ${neighbour.pos} while advancing generation stage of $this to $nextState (neighbour chunk was in state ${world.chunkMap[neighbour.pos]?.state}, expected $state)")
+								}
+							}
+						} catch (err: Throwable) {
+							LOGGER.error("Error while waiting on neighbouring chunks while generating this $this", err)
+							throw err
+						} finally {
+							neighbours.forEach { it.cancel() }
+						}
+					}
+
 					when (nextState) {
 						State.TILES -> {
 							// tiles can be generated concurrently without any consequences
@@ -98,15 +135,11 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 							//LOGGER.error("NYI: Generating cave liquids for $chunk")
 						}
 
-						State.TILE_ENTITIES -> {
-							//LOGGER.error("NYI: Generating tile entities for $chunk")
+						State.FULL -> {
+							CompletableFuture.runAsync(Runnable { placeGrass() }, Starbound.EXECUTOR).await()
 						}
 
-						State.ENTITIES -> {
-							//LOGGER.error("NYI: Placing entities for $chunk")
-						}
-
-						else -> {}
+						State.FRESH -> throw RuntimeException()
 					}
 
 					bumpState(nextState)
@@ -145,7 +178,11 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 				chunkGeneratorLoop()
 			}
 		} catch (err: Throwable) {
-			LOGGER.error("Exception while loading chunk $this", err)
+			if (err is CancellationException) {
+				// harmless
+			} else {
+				LOGGER.error("Exception while loading chunk $this", err)
+			}
 		}
 	}
 
@@ -224,8 +261,6 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 
 			if (this@ServerChunk.state >= targetState) {
 				chunk.complete(this@ServerChunk)
-			} else {
-				this@ServerChunk.targetState.trySend(targetState)
 			}
 		}
 
@@ -248,6 +283,8 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 	private inner class Ticket(state: State) : AbstractTicket(state) {
 		init {
 			permanent.add(this)
+
+			this@ServerChunk.targetState.trySend(targetState)
 		}
 
 		override fun cancel0() {
@@ -255,7 +292,7 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 		}
 	}
 
-	private inner class TimedTicket(expiresAt: Int, state: ServerChunk.State) : AbstractTicket(state), ITimedTicket {
+	private inner class TimedTicket(expiresAt: Int, state: State) : AbstractTicket(state), ITimedTicket {
 		var expiresAt = expiresAt + ticks
 
 		override val timeRemaining: Int
@@ -263,6 +300,7 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 
 		init {
 			temporary.add(this)
+			this@ServerChunk.targetState.trySend(targetState)
 		}
 
 		override fun cancel0() {
@@ -284,14 +322,8 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 
 	private fun bumpState(newState: State) {
 		if (newState == state) return
-
 		require(newState >= state) { "Tried to downgrade $this state from $state to $newState" }
-
-		if (newState >= State.ENTITIES) {
-			this.state = State.FULL
-		} else {
-			this.state = newState
-		}
+		this.state = newState
 
 		val permanent: List<Ticket>
 		val temporary: List<TimedTicket>
@@ -432,7 +464,9 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 		if (shouldUnload) {
 			idleTicks++
 			// don't load-save-load-save too frequently
-			shouldUnload = idleTicks > 600
+			// also make partially-generated chunks stay in memory for way longer, because re-generating
+			// them is very costly operation
+			shouldUnload = if (state == State.FULL) idleTicks > 600 else idleTicks > 32000
 		} else {
 			idleTicks = 0
 		}
@@ -507,7 +541,7 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 		}
 	}
 
-	fun prepareCells() {
+	private fun prepareCells() {
 		val cells = cells.value
 
 		for (x in 0 until width) {
@@ -563,6 +597,91 @@ class ServerChunk(world: ServerWorld, pos: ChunkPos) : Chunk<ServerWorld, Server
 		}
 	}
 
+	private fun placeGrass() {
+		for (x in 0 until width) {
+			for (y in 0 until height) {
+				placeGrass(x, y)
+			}
+		}
+	}
+
+	private fun placeGrass(x: Int, y: Int) {
+		val biome = world.template.cellInfo(pos.tileX + x, pos.tileY + y).blockBiome ?: return
+		val cell = cells.value[x, y]
+
+		// determine layer for grass mod calculation
+		val isBackground = cell.foreground.material.isEmptyTile
+
+		val tile = cell.tile(isBackground)
+		val tileInv = cell.tile(!isBackground)
+
+		// don't place mods in dungeons unless explicitly specified, also don't
+		// touch non-grass mods
+		if (
+			tile.modifier == BuiltinMetaMaterials.BIOME_MOD ||
+			tile.modifier == BuiltinMetaMaterials.UNDERGROUND_BIOME_MOD ||
+			(cell.dungeonId == NO_DUNGEON_ID && tile.modifier == BuiltinMetaMaterials.EMPTY_MOD)
+		) {
+			// check whether we're floor or ceiling
+
+			// NOTE: we are querying other chunks while generating,
+			// and we might read stale data if we are reading neighbouring chunks
+			// since they might be in process of generation, too
+			// (only if they are in process of generating someing significant, which modify terrain)
+			// shouldn't be an issue though
+			val cellAbove = world.chunkMap.getCell(pos.tileX + x, pos.tileY + y + 1)
+			val cellBelow = world.chunkMap.getCell(pos.tileX + x, pos.tileY + y - 1)
+
+			val tileAbove = cell.tile(isBackground)
+			val tileBelow = cell.tile(isBackground)
+			val tileAboveInv = cell.tile(!isBackground)
+			val tileBelowInv = cell.tile(!isBackground)
+
+			val isFloor = (!cell.foreground.material.isEmptyTile && cellAbove.foreground.material.isEmptyTile) || (!cell.background.material.isEmptyTile && cellAbove.background.material.isEmptyTile)
+			val isCeiling = !isFloor && ((!cell.foreground.material.isEmptyTile && cellBelow.foreground.material.isEmptyTile) || (!cell.background.material.isEmptyTile && cellBelow.background.material.isEmptyTile))
+
+			// I might be stupid, but in original code the check above is completely wrong
+			// because it will result in buried glass under tiles
+			//val isFloor = !tile.material.isEmptyTile && tileAbove.material.isEmptyTile
+			//val isCeiling = !isFloor && !tile.material.isEmptyTile && tileBelow.material.isEmptyTile
+
+			// get the appropriate placeables for above/below ground
+			val placeables = if (isFloor && !cellAbove.background.material.isEmptyTile || isCeiling && !cellBelow.background.material.isEmptyTile) {
+				biome.undergroundPlaceables
+			} else {
+				biome.surfacePlaceables
+			}
+
+			// determine the proper grass mod or lack thereof
+			var grassMod = BuiltinMetaMaterials.EMPTY_MOD
+
+			if (isFloor) {
+				if (staticRandomDouble(world.template.seed, pos.tileX + x, pos.tileY + y, "grass") <= placeables.grassModDensity) {
+					grassMod = placeables.grassMod.native.entry ?: BuiltinMetaMaterials.EMPTY_MOD
+				}
+			} else if (isCeiling) {
+				if (staticRandomDouble(world.template.seed, pos.tileX + x, pos.tileY + y, "grass") <= placeables.ceilingGrassModDensity) {
+					grassMod = placeables.ceilingGrassMod.native.entry ?: BuiltinMetaMaterials.EMPTY_MOD
+				}
+			}
+
+			val modify = cell.mutable()
+
+			if (isBackground) {
+				modify.background.modifier = grassMod
+				modify.foreground.modifier = BuiltinMetaMaterials.EMPTY_MOD
+			} else {
+				modify.foreground.modifier = grassMod
+				modify.background.modifier = BuiltinMetaMaterials.EMPTY_MOD
+			}
+
+			modify.background.modifierHueShift = biome.hueShift(modify.background.modifier)
+			modify.foreground.modifierHueShift = biome.hueShift(modify.foreground.modifier)
+
+			cells.value[x, y] = modify.immutable()
+		}
+	}
+
 	companion object {
 		private val LOGGER = LogManager.getLogger()
 	}
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorld.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorld.kt
index 2dc1deb3..ed1ae8a2 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorld.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorld.kt
@@ -91,7 +91,7 @@ class ServerWorld private constructor(
 			if (action != null)
 				client.send(PlayerWarpResultPacket(true, action, false))
 
-			client.tracker?.remove("Transiting to new world")
+			client.tracker?.remove("Transiting to new world", false)
 			clients.add(ServerWorldTracker(this, client, start))
 		} finally {
 			isBusy--
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorldTracker.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorldTracker.kt
index c1bc52cc..c9b5e323 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorldTracker.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorldTracker.kt
@@ -268,7 +268,7 @@ class ServerWorldTracker(val world: ServerWorld, val client: ServerConnection, p
 		}
 	}
 
-	fun remove(reason: String = "ServerWorldTracker got removed") {
+	fun remove(reason: String = "ServerWorldTracker got removed", nullifyVariables: Boolean = true) {
 		if (isRemoved.compareAndSet(false, true)) {
 			// erase all tasks just to be sure
 			tasks.clear()
@@ -279,9 +279,12 @@ class ServerWorldTracker(val world: ServerWorld, val client: ServerConnection, p
 				client.returnWarp = WarpAction.World(world.worldID, SpawnTarget.Position(playerEntity.position))
 			}
 
-			client.tracker = null
-			client.playerEntity = null
-			client.worldID = WorldID.Limbo
+			if (nullifyVariables) {
+				client.tracker = null
+				client.playerEntity = null
+				client.worldID = WorldID.Limbo
+			}
+
 			client.send(WorldStopPacket(reason))
 
 			// this handles case where player is removed from world and
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/world/ChunkPos.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/world/ChunkPos.kt
index df7b75e5..aa9567c8 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/world/ChunkPos.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/world/ChunkPos.kt
@@ -71,6 +71,10 @@ data class ChunkPos(val x: Int, val y: Int) : IStruct2i, Comparable<ChunkPos> {
 		return ChunkPos(x + 1, y)
 	}
 
+	fun neighbours(): List<ChunkPos> {
+		return listOf(top, bottom, left, right, topLeft, topRight, bottomLeft, bottomRight)
+	}
+
 	override fun equals(other: Any?): Boolean {
 		if (other is ChunkPos)
 			return other.x == x && other.y == y
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/AbstractCell.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/AbstractCell.kt
index a4eb403c..8d9bb25d 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/AbstractCell.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/AbstractCell.kt
@@ -2,6 +2,7 @@ package ru.dbotthepony.kstarbound.world.api
 
 import com.github.benmanes.caffeine.cache.Interner
 import ru.dbotthepony.kstarbound.Starbound
+import ru.dbotthepony.kstarbound.defs.tile.NO_DUNGEON_ID
 import ru.dbotthepony.kstarbound.network.LegacyNetworkCellState
 import java.io.DataInputStream
 import java.io.DataOutputStream
@@ -11,7 +12,7 @@ sealed class AbstractCell {
 	abstract val background: AbstractTileState
 	abstract val liquid: AbstractLiquidState
 
-	// ushort, can be anything (but 65535), mostly used by placed dungeons
+	// ushort, can be anything, mostly used by placed dungeons
 	// this value determines special logic behind this cell, such as if it is protected from modifications
 	// by players or other means
 	abstract val dungeonId: Int
@@ -63,7 +64,7 @@ sealed class AbstractCell {
 		@JvmStatic
 		protected val POOL: Interner<ImmutableCell> = if (Starbound.DEDUP_CELL_STATES) Starbound.interner() else Interner { it }
 
-		val EMPTY: ImmutableCell = POOL.intern(ImmutableCell(AbstractTileState.EMPTY, AbstractTileState.EMPTY, AbstractLiquidState.EMPTY, 0, 0, 0, false))
-		val NULL: ImmutableCell = POOL.intern(ImmutableCell(AbstractTileState.NULL, AbstractTileState.NULL, AbstractLiquidState.EMPTY, 0, 0, 0, false))
+		val EMPTY: ImmutableCell = POOL.intern(ImmutableCell(AbstractTileState.EMPTY, AbstractTileState.EMPTY, AbstractLiquidState.EMPTY, NO_DUNGEON_ID, 0, 0, false))
+		val NULL: ImmutableCell = POOL.intern(ImmutableCell(AbstractTileState.NULL, AbstractTileState.NULL, AbstractLiquidState.EMPTY, NO_DUNGEON_ID, 0, 0, false))
 	}
 }
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/ImmutableCell.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/ImmutableCell.kt
index bb631637..82b3a8c0 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/ImmutableCell.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/ImmutableCell.kt
@@ -1,5 +1,6 @@
 package ru.dbotthepony.kstarbound.world.api
 
+import ru.dbotthepony.kstarbound.defs.tile.NO_DUNGEON_ID
 import ru.dbotthepony.kstarbound.network.LegacyNetworkCellState
 
 data class ImmutableCell(
@@ -7,7 +8,7 @@ data class ImmutableCell(
 	override val background: ImmutableTileState = AbstractTileState.EMPTY,
 	override val liquid: ImmutableLiquidState = AbstractLiquidState.EMPTY,
 
-	override val dungeonId: Int = 0,
+	override val dungeonId: Int = NO_DUNGEON_ID,
 	override val blockBiome: Int = 0,
 	override val envBiome: Int = 0,
 	override val isIndestructible: Boolean = false,
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/ImmutableTileState.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/ImmutableTileState.kt
index 3ca47a36..e77a9328 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/ImmutableTileState.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/ImmutableTileState.kt
@@ -7,11 +7,11 @@ import ru.dbotthepony.kstarbound.defs.tile.TileDefinition
 import ru.dbotthepony.kstarbound.network.LegacyNetworkTileState
 
 data class ImmutableTileState(
-	override var material: Registry.Entry<TileDefinition> = BuiltinMetaMaterials.NULL,
-	override var modifier: Registry.Entry<TileModifierDefinition> = BuiltinMetaMaterials.EMPTY_MOD,
-	override var color: TileColor = TileColor.DEFAULT,
-	override var hueShift: Float = 0f,
-	override var modifierHueShift: Float = 0f,
+	override val material: Registry.Entry<TileDefinition> = BuiltinMetaMaterials.NULL,
+	override val modifier: Registry.Entry<TileModifierDefinition> = BuiltinMetaMaterials.EMPTY_MOD,
+	override val color: TileColor = TileColor.DEFAULT,
+	override val hueShift: Float = 0f,
+	override val modifierHueShift: Float = 0f,
 ) : AbstractTileState() {
 	override fun immutable(): ImmutableTileState {
 		return this
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/MutableCell.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/MutableCell.kt
index 4a323279..29e6a329 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/MutableCell.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/world/api/MutableCell.kt
@@ -1,5 +1,6 @@
 package ru.dbotthepony.kstarbound.world.api
 
+import ru.dbotthepony.kstarbound.defs.tile.NO_DUNGEON_ID
 import java.io.DataInputStream
 
 data class MutableCell(
@@ -7,7 +8,7 @@ data class MutableCell(
 	override val background: MutableTileState = MutableTileState(),
 	override val liquid: MutableLiquidState = MutableLiquidState(),
 
-	override var dungeonId: Int = 0,
+	override var dungeonId: Int = NO_DUNGEON_ID,
 	override var blockBiome: Int = 0,
 	override var envBiome: Int = 0,
 	override var isIndestructible: Boolean = false,