diff --git a/2019/aoc2019/day24.py b/2019/aoc2019/day24.py
index 9dced01..62cb729 100644
--- a/2019/aoc2019/day24.py
+++ b/2019/aoc2019/day24.py
@@ -1,4 +1,4 @@
-from typing import TextIO, Iterable, Tuple
+from typing import TextIO, Iterable, Tuple, List
 
 
 def read_board(data: TextIO) -> Tuple[Tuple[bool]]:
@@ -45,6 +45,77 @@ def advance_board(board: Tuple[Tuple[bool]]) -> Tuple[Tuple[bool]]:
     return tuple(create_row(y, row) for y, row in enumerate(board))
 
 
+def neighbours2(board: List[Tuple[Tuple[bool]]], x: int, y: int, z: int) -> int:
+    existing = range(len(board))
+
+    if z in existing:
+        # Normal board count, minus the middle tile if applicable
+        n = neighbours(board[z], x, y) - board[z][2][2]
+    else:
+        n = 0
+
+    if z - 1 in existing:
+        if y == 2:
+            if x == 1:
+                n += sum(board[z - 1][iy][0] for iy in range(5))
+            elif x == 3:
+                n += sum(board[z - 1][iy][4] for iy in range(5))
+        elif x == 2:
+            if y == 1:
+                n += sum(board[z - 1][0])
+            elif y == 3:
+                n += sum(board[z - 1][4])
+
+    if z + 1 in existing:
+        if y == 0:
+            n += board[z + 1][1][2]
+        elif y == 4:
+            n += board[z + 1][3][2]
+
+        if x == 0:
+            n += board[z + 1][2][1]
+        elif x == 4:
+            n += board[z + 1][2][3]
+
+    return n
+
+
+def advance_board2(board: List[Tuple[Tuple[bool]]]) -> List[Tuple[Tuple[bool]]]:
+    layers = []
+
+    for z in range(-1, len(board) + 1):
+        layer = []
+
+        for y in range(5):
+            row = []
+
+            for x in range(5):
+                if y == 2 and x == 2:
+                    row.append(False)
+                    continue
+
+                if z in range(len(board)):
+                    live = board[z][y][x]
+                else:
+                    live = False
+
+                if live:
+                    row.append(neighbours2(board, x, y, z) == 1)
+                else:
+                    row.append(neighbours2(board, x, y, z) in [1, 2])
+
+            layer.append(tuple(row))
+
+        layers.append(tuple(layer))
+
+    if sum(flatten(layers[0])) == 0:
+        layers = layers[1:]
+    if sum(flatten(layers[-1])) == 0:
+        layers = layers[:-1]
+
+    return layers
+
+
 def part1(data: TextIO) -> int:
     board = read_board(data)
 
@@ -56,3 +127,12 @@ def part1(data: TextIO) -> int:
             return sum(2 ** i for i, b in enumerate(flatten(board)) if b)
 
         seen.add(board)
+
+
+def part2(data: TextIO, rounds: int = 200) -> int:
+    board = [read_board(data)]
+
+    for _ in range(rounds):
+        board = advance_board2(board)
+
+    return sum(flatten(flatten(board)))