diff --git a/shenzhen_solitaire/board.py b/shenzhen_solitaire/board.py
index a8565c8..710410c 100644
--- a/shenzhen_solitaire/board.py
+++ b/shenzhen_solitaire/board.py
@@ -8,10 +8,14 @@ import itertools
 class SpecialCard(enum.Enum):
     """Different types of special cards"""
 
-    Zhong = enum.auto()
-    Bai = enum.auto()
-    Fa = enum.auto()
-    Hua = enum.auto()
+    Zhong = 0
+    Bai = 1
+    Fa = 2
+    Hua = 3
+
+    def identifier(self) -> int:
+        """Returns unique identifier representing this card"""
+        return int(self.value)
 
 
 @dataclass(frozen=True)
@@ -21,12 +25,16 @@ class NumberCard:
     class Suit(enum.Enum):
         """Different colors number cards can have"""
 
-        Red = enum.auto()
-        Green = enum.auto()
-        Black = enum.auto()
+        Red = 0
+        Green = 1
+        Black = 2
 
     suit: Suit
-    number: int
+    number: int  # [1 - 9]
+
+    def identifier(self) -> int:
+        """Returns unique identifier representing this card"""
+        return int(self.number - 1 + 9 ** int(self.suit.value))
 
 
 Card = Union[NumberCard, SpecialCard]
@@ -45,14 +53,52 @@ class Board:
 
     def __init__(self) -> None:
         self.field: List[List[Card]] = [[]] * 8
-        self.bunker: List[Union[Tuple[SpecialCard, int], Optional[Card]]] = [None] * 3
+        self.bunker: List[Union[Tuple[SpecialCard, int],
+                                Optional[Card]]] = [None] * 3
         self.goal: Dict[NumberCard.Suit, int] = {
             NumberCard.Suit.Red: 0,
             NumberCard.Suit.Green: 0,
             NumberCard.Suit.Black: 0,
         }
+        self.flower_gone: bool = False
 
-    flowerGone: bool = False
+    def state_identifier(self) -> int:
+        """Returns a unique identifier to represent the board state"""
+        result: int = 0
+        for card in self.bunker:
+            result <<= 2
+            if isinstance(card, tuple):
+                result |= 0
+                result <<= 2
+                result |= card[0].identifier()  # pylint: disable=E1136
+            elif card is None:
+                result |= 1
+            else:
+                result |= 2
+                result <<= 5
+                result |= card.identifier()
+
+
+        result <<= 1
+        if self.flower_gone:
+            result |= 1
+
+        for _, goal_count in self.goal.items():
+            result <<= 4
+            result |= goal_count
+
+        # Max stack size is 13 (4 random cards from the start, plus a stack from 9 to 1]
+        # So 4 bits are sufficient
+        for stack in self.field:
+            assert len(stack) == len(stack) & 0b1111
+            result <<= 4
+            result |= len(stack)
+
+        for field_card in itertools.chain.from_iterable(self.field):
+            result <<= 5
+            result |= field_card.identifier()
+
+        return 0
 
     def check_correct(self) -> bool:
         """Returns true, if the board is in a valid state"""
@@ -68,13 +114,12 @@ class Board:
             SpecialCard.Hua: 0,
         }
 
-        if self.flowerGone:
+        if self.flower_gone:
             special_cards[SpecialCard.Hua] += 1
 
         for card in itertools.chain(
-            self.bunker,
-            itertools.chain.from_iterable(stack for stack in self.field if stack),
-        ):
+            self.bunker, itertools.chain.from_iterable(
+                stack for stack in self.field if stack), ):
             if isinstance(card, tuple):
                 special_cards[card[0]] += 4  # pylint: disable=E1136
             elif isinstance(card, SpecialCard):
diff --git a/shenzhen_solitaire/board_actions.py b/shenzhen_solitaire/board_actions.py
index 1620e24..40e9949 100644
--- a/shenzhen_solitaire/board_actions.py
+++ b/shenzhen_solitaire/board_actions.py
@@ -91,9 +91,11 @@ class MoveAction:
 
         if action_board.field[dest]:
             dest_card = action_board.field[dest][-1]
+            if not all(isinstance(x, board.NumberCard) for x in self.cards):
+                raise AssertionError()
             if not isinstance(dest_card, board.NumberCard):
                 raise AssertionError()
-            if not all(isinstance(x, board.NumberCard) for x in self.cards):
+            if not isinstance(self.cards[0], board.NumberCard):
                 raise AssertionError()
             if dest_card.suit == self.cards[0].suit:
                 raise AssertionError()
@@ -161,16 +163,16 @@ class HuaKillAction:
 
     def apply(self, action_board: board.Board) -> None:
         """Do action"""
-        assert not action_board.flowerGone
+        assert not action_board.flower_gone
         assert action_board.field[self.source_field_id][-1] == board.SpecialCard.Hua
         action_board.field[self.source_field_id].pop()
-        action_board.flowerGone = True
+        action_board.flower_gone = True
 
     def undo(self, action_board: board.Board) -> None:
         """Undo action"""
-        assert action_board.flowerGone
+        assert action_board.flower_gone
         action_board.field[self.source_field_id].append(board.SpecialCard.Hua)
-        action_board.flowerGone = False
+        action_board.flower_gone = False
 
 
 Action = Union[MoveAction, DragonKillAction, HuaKillAction, BunkerizeAction, GoalAction]
diff --git a/test/context.py b/test/context.py
index c0199b4..90f0c95 100644
--- a/test/context.py
+++ b/test/context.py
@@ -3,5 +3,3 @@ import os
 import sys
 sys.path.insert(0, os.path.abspath(
     os.path.join(os.path.dirname(__file__), '..')))
-
-import shenzhen_solitaire
diff --git a/test/test_chain.py b/test/test_chain.py
index 0a8b23b..f072e31 100644
--- a/test/test_chain.py
+++ b/test/test_chain.py
@@ -1,7 +1,7 @@
 """Contains tests for chain module"""
 import unittest
 
-from .context import shenzhen_solitaire  # pylint: disable=unused-import
+from . import context   # pylint: disable=unused-import
 from shenzhen_solitaire.board import NumberCard, SpecialCard, Board  # pylint: disable=wrong-import-order
 from shenzhen_solitaire import board_possibilities  # pylint: disable=wrong-import-order