diff --git a/src/aiocraft/mc/chunk.py b/src/aiocraft/mc/chunk.py
new file mode 100644
index 0000000..c533be0
--- /dev/null
+++ b/src/aiocraft/mc/chunk.py
@@ -0,0 +1,190 @@
+import io
+import math
+import logging
+
+from typing import Dict, Tuple, Any
+
+import numpy as np
+
+from aiocraft.mc.types import VarInt, Short, UnsignedByte, Type, Context
+
+class BitStream:
+	data : bytes
+	cursor : int
+	size : int
+	def __init__(self, data:bytes, size:int):
+		self.data = data
+		self.cursor = 0
+		self.size = size if size > 0 else len(self.data) * 8
+	def __len__(self) -> int:
+		return self.size - self.cursor
+	def read(self, size:int) -> int:
+		if len(self) < size:
+			raise ValueError(f"Not enough bits ({len(self)} left, {size} requested)")
+		# Calculate splice indexes
+		start_byte = (self.cursor//8)
+		end_byte = math.ceil((self.cursor + size) / 8)
+		# Construct int from bytes
+		buf = int.from_bytes(
+			self.data[start_byte:end_byte],
+			byteorder='little', signed=False
+		)
+		# Trim extra bytes
+		end_offset = (self.cursor + size) % 8
+		if end_offset > 0:
+			buf = buf >> (8 - end_offset) # There's an extra 1 to the left in air, maybe shift 1 bit less?
+		start_offset = self.cursor % 8
+		buf = buf & (( 1 << size ) - 1)
+		# Increment and return
+		self.cursor += size
+		return buf
+
+class PalettedContainer(Type):
+	pytype : type
+	threshold : int
+	size : int
+
+	def __init__(self, threshold:int, size:int):
+		self.threshold = threshold
+		self.size = size
+
+	def write(self, data, buffer:io.BytesIO, ctx:Context):
+		raise NotImplementedError
+
+	def read(self, buffer:io.BytesIO, ctx:Context):
+		bits = UnsignedByte.read(buffer, ctx=ctx) # FIXME if bits > 4 it reads trash
+		if bits < 4:
+			bits = 4
+		if bits >= self.threshold:
+			bits = 13 # this should not be hardcoded but we have no way to calculate all possible block states
+		palette_len = VarInt.read(buffer, ctx=ctx)
+		palette = np.zeros((palette_len,), dtype='int32')
+		for i in range(palette_len):
+			palette[i] = VarInt.read(buffer, ctx=ctx)
+		container_size = VarInt.read(buffer, ctx=ctx)
+		stream = BitStream(buffer.read(container_size * 8), container_size*8*8) # a Long is 64 bits long
+		section = np.zeros((self.size, self.size, self.size), dtype='int32')
+		for y in range(self.size):
+			for z in range(self.size):
+				for x in range(self.size):
+					val = stream.read(bits)
+					if val >= len(palette):
+						logging.warning("out of bounds : %d (%d)", val, len(palette)) # FIXME happens a lot!
+						section[x, y, z] = val
+						continue
+					section[x, y, z] = palette[val] if bits < self.threshold else val
+		return section
+
+BiomeContainer = PalettedContainer(4, 4)
+BlockStateContainer = PalettedContainer(9, 16)
+
+class HalfByteArrayType(Type):
+	size : int
+
+	def __init__(self, size:int):
+		self.size = size
+
+	def write(self, data, buffer:io.BytesIO, ctx:Context):
+		raise NotImplementedError
+
+	def read(self, buffer:io.BytesIO, ctx:Context):
+		section = np.empty((self.size, self.size, self.size), dtype='int32')
+		bit_buffer = BitStream(buffer.read((self.size**3)//2), (self.size**3)*4)
+		for y in range(self.size):
+			for z in range(self.size):
+				for x in range(self.size):
+					section[x, y, z] = bit_buffer.read(4)
+		return section
+
+BlockLightSection = HalfByteArrayType(16)
+SkyLightSection = HalfByteArrayType(16)
+
+class NewChunkSectionType(Type):
+	pytype : type
+
+	def write(self, data, buffer:io.BytesIO, ctx:Context):
+		raise NotImplementedError
+
+	def read(self, buffer:io.BytesIO, ctx:Context):
+		block_count = Short.read(buffer, ctx=ctx)
+		block_states = BlockStateContainer.read(buffer, ctx=ctx)
+		biomes = BiomeContainer.read(buffer, ctx=ctx)
+		return (
+			block_count,
+			block_states,
+			biomes
+		)
+
+class OldChunkSectionType(Type):
+	pytype : type
+
+	def write(self, data, buffer:io.BytesIO, ctx:Context):
+		raise NotImplementedError
+
+	def read(self, buffer:io.BytesIO, ctx:Context):
+		block_states = BlockStateContainer.read(buffer, ctx=ctx)
+		block_light = BlockLightSection.read(buffer, ctx=ctx)
+		if ctx.overworld:
+			sky_light = SkyLightSection.read(buffer, ctx=ctx)
+		else:
+			sky_light = np.empty((16, 16, 16), dtype='int32')
+		return (
+			block_states,
+			block_light,
+			sky_light
+		)
+
+ChunkSection = OldChunkSectionType()
+
+class Chunk(Type):
+	x : int
+	z : int
+	bitmask : int
+	ground_up_continuous : bool
+	blocks : np.ndarray
+	block_light : np.ndarray
+	sky_light : np.ndarray
+	biomes: bytes
+
+	def __init__(self, x:int, z:int, bitmask:int, ground_up_continuous:bool):
+		self.x = x
+		self.z = z
+		self.bitmask = bitmask
+		self.blocks = np.zeros((16, 256, 16), dtype='int32')
+		self.block_light = np.zeros((16, 256, 16), dtype='int32')
+		self.sky_light = np.zeros((16, 256, 16), dtype='int32')
+		self.ground_up_continuous = ground_up_continuous
+
+	def __getitem__(self, item:Any):
+		return self.blocks[item]
+
+	def read(self, buffer:io.BytesIO, ctx:Context):
+		for i in range(16):
+			if (self.bitmask >> i) & 1:
+				block_states, block_light, sky_light = ChunkSection.read(buffer, ctx=ctx)
+				self.blocks[:, i*16 : (i+1)*16, :] = block_states
+				self.block_light[:, i*16 : (i+1)*16, :] = block_light
+				self.sky_light[:, i*16 : (i+1)*16, :] = sky_light
+		if self.ground_up_continuous:
+			self.biomes = buffer.read(256) # 16x16
+		if buffer.read():
+			logging.warning("Leftover data in chunk buffer")
+		return self
+
+class World:
+	chunks : Dict[Tuple[int, int], Chunk]
+
+	def __init__(self):
+		self.chunks = {}
+
+	def __getitem__(self, item:Tuple[int, int, int]):
+		return self.get(*item)
+
+	def get(self, x:int, y:int, z:int) -> int:
+		coord = (x//16, z//16)
+		if coord not in self.chunks:
+			raise KeyError(f"Chunk {coord} not loaded")
+		return self.chunks[coord][int(x%16), int(y), int(z%16)]
+
+	def put(self, chunk:Chunk, x:int, z:int):
+		self.chunks[(x,z)] = chunk