diff --git a/pgx/othello.py b/pgx/othello.py
index 449e5633f..bc7183ca7 100644
--- a/pgx/othello.py
+++ b/pgx/othello.py
@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from typing import NamedTuple
+
 import jax
 import jax.numpy as jnp
 
@@ -23,17 +25,8 @@
 TRUE = jnp.bool_(True)
 
 
-@dataclass
-class State(core.State):
-    current_player: Array = jnp.int32(0)
-    observation: Array = jnp.zeros((8, 8, 2), dtype=jnp.bool_)
-    rewards: Array = jnp.float32([0.0, 0.0])
-    terminated: Array = FALSE
-    truncated: Array = FALSE
-    legal_action_mask: Array = jnp.ones(64 + 1, dtype=jnp.bool_)
-    _step_count: Array = jnp.int32(0)
-    # --- Othello specific ---
-    _turn: Array = jnp.int32(0)
+class GameState(NamedTuple):
+    turn: Array = jnp.int32(0)
     # 8x8 board
     # [[ 0,  1,  2,  3,  4,  5,  6,  7],
     #  [ 8,  9, 10, 11, 12, 13, 14, 15],
@@ -43,8 +36,20 @@ class State(core.State):
     #  [40, 41, 42, 43, 44, 45, 46, 47],
     #  [48, 49, 50, 51, 52, 53, 54, 55],
     #  [56, 57, 58, 59, 60, 61, 62, 63]]
-    _board: Array = jnp.zeros(64, jnp.int32)  # -1(opp), 0(empty), 1(self)
-    _passed: Array = FALSE
+    board: Array = jnp.zeros(64, jnp.int32)
+    passed: Array = jnp.bool_(False)
+
+
+@dataclass
+class State(core.State):
+    current_player: Array = jnp.int32(0)
+    observation: Array = jnp.zeros((8, 8, 2), dtype=jnp.bool_)
+    rewards: Array = jnp.float32([0.0, 0.0])
+    terminated: Array = FALSE
+    truncated: Array = FALSE
+    legal_action_mask: Array = jnp.ones(64 + 1, dtype=jnp.bool_)
+    _step_count: Array = jnp.int32(0)
+    _x: GameState = GameState()
 
     @property
     def env_id(self) -> core.EnvId:
@@ -107,7 +112,10 @@ def _init(rng: PRNGKey) -> State:
     current_player = jnp.int32(jax.random.bernoulli(rng))
     return State(
         current_player=current_player,
-        _board=jnp.zeros(64, dtype=jnp.int32).at[28].set(1).at[35].set(1).at[27].set(-1).at[36].set(-1),
+        _x=GameState(
+            turn=0,
+            board=jnp.zeros(64, dtype=jnp.int32).at[28].set(1).at[35].set(1).at[27].set(-1).at[36].set(-1),
+        ),
         legal_action_mask=jnp.zeros(64 + 1, dtype=jnp.bool_)
         .at[19]
         .set(TRUE)
@@ -121,7 +129,7 @@ def _init(rng: PRNGKey) -> State:
 
 
 def _step(state, action):
-    board = state._board
+    board = state._x.board
     my = board > 0
     opp = board < 0
 
@@ -167,19 +175,21 @@ def _make_legal(i, legal):
     legal_action = jax.lax.fori_loop(0, 8, _make_legal, jnp.zeros(64, dtype=jnp.bool_))
 
     reward, terminated = jax.lax.cond(
-        ((jnp.count_nonzero(my | opp) == 64) | ~opp.any() | (state._passed & (action == 64))),
+        ((jnp.count_nonzero(my | opp) == 64) | ~opp.any() | (state._x.passed & (action == 64))),
         lambda: (_get_reward(my, opp, state.current_player), TRUE),
         lambda: (jnp.zeros(2, jnp.float32), FALSE),
     )
 
     return state.replace(
         current_player=1 - state.current_player,
-        _turn=1 - state._turn,
+        _x=GameState(
+            turn=1 - state._x.turn,
+            board=-jnp.where(jnp.int32(opp), -1, jnp.int32(my)),
+            passed=action == 64,
+        ),
         legal_action_mask=state.legal_action_mask.at[:64].set(legal_action).at[64].set(~legal_action.any()),
         rewards=reward,
         terminated=terminated,
-        _board=-jnp.where(jnp.int32(opp), -1, jnp.int32(my)),
-        _passed=action == 64,
     )
 
 
@@ -208,8 +218,8 @@ def _get_reward(my, opp, curr_player):
 def _observe(state, player_id) -> Array:
     board = jax.lax.cond(
         player_id == state.current_player,
-        lambda: state._board.reshape((8, 8)),
-        lambda: (state._board * -1).reshape((8, 8)),
+        lambda: state._x.board.reshape((8, 8)),
+        lambda: (state._x.board * -1).reshape((8, 8)),
     )
 
     def make(color):
@@ -219,4 +229,4 @@ def make(color):
 
 
 def _get_abs_board(state):
-    return jax.lax.cond(state._turn == 0, lambda: state._board, lambda: state._board * -1)
+    return jax.lax.cond(state._x.turn == 0, lambda: state._x.board, lambda: state._x.board * -1)
diff --git a/tests/test_othello.py b/tests/test_othello.py
index 1f7b69cde..cae8981e8 100644
--- a/tests/test_othello.py
+++ b/tests/test_othello.py
@@ -37,7 +37,7 @@ def test_step():
         0, 0, 0, 0, 0, 0, 0, 0,
         0, 0, 0, 0, 0, 0, 0, 0])
     # fmt:on
-    assert jnp.all(state._board == expected)
+    assert jnp.all(state._x.board == expected)
 
 
 def test_terminated():