diff --git a/src/samples/onitama/commands.ts b/src/samples/onitama/commands.ts
index 917fb44..78aaa6e 100644
--- a/src/samples/onitama/commands.ts
+++ b/src/samples/onitama/commands.ts
@@ -1,379 +1,409 @@
 import {
-    OnitamaGame,
-    OnitamaState,
-    PlayerType,
-    prompts,
-    initializeCards
+  OnitamaGame,
+  OnitamaState,
+  PlayerType,
+  prompts,
+  initializeCards,
 } from "./types";
-import {createGameCommandRegistry} from "@/core/game";
-import {moveToRegion} from "@/core/region";
-
-export const registry = createGameCommandRegistry<OnitamaState>();
+import { moveToRegion } from "@/core/region";
 
 /**
  * 检查位置是否在棋盘范围内
  */
 function isInBounds(x: number, y: number): boolean {
-    return x >= 0 && x < 5 && y >= 0 && y < 5;
+  return x >= 0 && x < 5 && y >= 0 && y < 5;
 }
 
 /**
  * 检查位置是否有棋子
  */
 function getPawnAtPosition(state: OnitamaState, x: number, y: number) {
-    const key = `${x},${y}`;
-    const pawnId = state.regions.board.partMap[key];
-    return pawnId ? state.pawns[pawnId] : null;
+  const key = `${x},${y}`;
+  const pawnId = state.regions.board.partMap[key];
+  return pawnId ? state.pawns[pawnId] : null;
 }
 
 /**
  * 检查玩家是否拥有某张卡牌
  */
-function playerHasCard(state: OnitamaState, player: PlayerType, cardName: string): boolean {
-    const cardList = player === 'red' ? state.redCards : state.blackCards;
-    return cardList.includes(cardName);
+function playerHasCard(
+  state: OnitamaState,
+  player: PlayerType,
+  cardName: string,
+): boolean {
+  const cardList = player === "red" ? state.redCards : state.blackCards;
+  return cardList.includes(cardName);
 }
 
 /**
  * 获取卡牌的移动候选项，根据玩家视角进行旋转
  * 黑方需要将卡牌旋转180度
  */
-export function getCardMoveCandidates(state: OnitamaState, cardName: string, player: PlayerType) {
-    const card = state.cards[cardName];
-    const candidates = card.moveCandidates;
+export function getCardMoveCandidates(
+  state: OnitamaState,
+  cardName: string,
+  player: PlayerType,
+) {
+  const card = state.cards[cardName];
+  const candidates = card.moveCandidates;
 
-    // 黑方需要将卡牌旋转180度
-    if (player === 'black') {
-        return candidates.map(m => ({ dx: -m.dx, dy: -m.dy }));
-    }
+  // 黑方需要将卡牌旋转180度
+  if (player === "black") {
+    return candidates.map((m) => ({ dx: -m.dx, dy: -m.dy }));
+  }
 
-    return candidates;
+  return candidates;
 }
 
 /**
  * 检查移动是否合法
  */
-export function isValidMove(state: OnitamaState, cardName: string, fromX: number, fromY: number, toX: number, toY: number, player: PlayerType): string | null {
-    // 检查玩家是否拥有该卡牌
-    if (!playerHasCard(state, player, cardName)) {
-        return `玩家 ${player} 不拥有卡牌 ${cardName}`;
-    }
+export function isValidMove(
+  state: OnitamaState,
+  cardName: string,
+  fromX: number,
+  fromY: number,
+  toX: number,
+  toY: number,
+  player: PlayerType,
+): string | null {
+  // 检查玩家是否拥有该卡牌
+  if (!playerHasCard(state, player, cardName)) {
+    return `玩家 ${player} 不拥有卡牌 ${cardName}`;
+  }
 
-    // 检查起始位置是否有玩家的棋子
-    const fromPawn = getPawnAtPosition(state, fromX, fromY);
-    if (!fromPawn) {
-        return `位置 (${fromX}, ${fromY}) 没有棋子`;
-    }
-    if (fromPawn.owner !== player) {
-        return `位置 (${fromX}, ${fromY}) 的棋子不属于玩家 ${player}`;
-    }
+  // 检查起始位置是否有玩家的棋子
+  const fromPawn = getPawnAtPosition(state, fromX, fromY);
+  if (!fromPawn) {
+    return `位置 (${fromX}, ${fromY}) 没有棋子`;
+  }
+  if (fromPawn.owner !== player) {
+    return `位置 (${fromX}, ${fromY}) 的棋子不属于玩家 ${player}`;
+  }
 
-    // 检查卡牌是否存在
-    const card = state.cards[cardName];
-    if (!card) {
-        return `卡牌 ${cardName} 不存在`;
-    }
+  // 检查卡牌是否存在
+  const card = state.cards[cardName];
+  if (!card) {
+    return `卡牌 ${cardName} 不存在`;
+  }
 
-    // 计算移动偏移量
-    const dx = toX - fromX;
-    const dy = toY - fromY;
+  // 计算移动偏移量
+  const dx = toX - fromX;
+  const dy = toY - fromY;
 
-    // 检查移动是否在卡牌的移动候选项中（黑方需要旋转180度）
-    const candidates = getCardMoveCandidates(state, cardName, player);
-    const isValid = candidates.some(m => m.dx === dx && m.dy === dy);
-    if (!isValid) {
-        return `卡牌 ${cardName} 不支持移动 (${dx}, ${dy})`;
-    }
+  // 检查移动是否在卡牌的移动候选项中（黑方需要旋转180度）
+  const candidates = getCardMoveCandidates(state, cardName, player);
+  const isValid = candidates.some((m) => m.dx === dx && m.dy === dy);
+  if (!isValid) {
+    return `卡牌 ${cardName} 不支持移动 (${dx}, ${dy})`;
+  }
 
-    // 检查目标位置是否在棋盘内
-    if (!isInBounds(toX, toY)) {
-        return `目标位置 (${toX}, ${toY}) 超出棋盘范围`;
-    }
+  // 检查目标位置是否在棋盘内
+  if (!isInBounds(toX, toY)) {
+    return `目标位置 (${toX}, ${toY}) 超出棋盘范围`;
+  }
 
-    // 检查目标位置是否有己方棋子
-    const toPawn = getPawnAtPosition(state, toX, toY);
-    if (toPawn && toPawn.owner === player) {
-        return `目标位置 (${toX}, ${toY}) 已有己方棋子`;
-    }
+  // 检查目标位置是否有己方棋子
+  const toPawn = getPawnAtPosition(state, toX, toY);
+  if (toPawn && toPawn.owner === player) {
+    return `目标位置 (${toX}, ${toY}) 已有己方棋子`;
+  }
 
-    return null;
+  return null;
 }
 
 /**
  * 执行移动
  */
-async function handleMove(game: OnitamaGame, player: PlayerType, cardName: string, fromX: number, fromY: number, toX: number, toY: number) {
-    const state = game.value;
-    
-    // 验证移动
-    const error = isValidMove(state, cardName, fromX, fromY, toX, toY, player);
-    if (error) {
-        throw new Error(error);
-    }
-    
-    const capturedPawnId = getPawnAtPosition(state, toX, toY)?.id || null;
-    
-    await game.produceAsync(state => {
-        const pawn = state.pawns[getPawnAtPosition(state, fromX, fromY)!.id];
-        
-        // 如果目标位置有敌方棋子，将其移除（吃掉）
-        if (capturedPawnId) {
-            const capturedPawn = state.pawns[capturedPawnId];
-            moveToRegion(capturedPawn, state.regions.board, null);
-        }
-        
-        // 移动棋子到目标位置
-        moveToRegion(pawn, state.regions.board, state.regions.board, [toX, toY]);
-    });
-    
-    // 交换卡牌
-    await handleSwapCard(game, player, cardName);
-    
-    return { 
-        from: { x: fromX, y: fromY }, 
-        to: { x: toX, y: toY }, 
-        card: cardName,
-        captured: capturedPawnId 
-    };
-}
+async function move(
+  game: OnitamaGame,
+  player: PlayerType,
+  cardName: string,
+  fromX: number,
+  fromY: number,
+  toX: number,
+  toY: number,
+) {
+  const state = game.value;
 
-const move = registry.register({
-    schema: 'move <player> <card:string> <fromX:number> <fromY:number> <toX:number> <toY:number>',
-    run: handleMove
-});
+  // 验证移动
+  const error = isValidMove(state, cardName, fromX, fromY, toX, toY, player);
+  if (error) {
+    throw new Error(error);
+  }
+
+  const capturedPawnId = getPawnAtPosition(state, toX, toY)?.id || null;
+
+  await game.produceAsync((state) => {
+    const pawn = state.pawns[getPawnAtPosition(state, fromX, fromY)!.id];
+
+    // 如果目标位置有敌方棋子，将其移除（吃掉）
+    if (capturedPawnId) {
+      const capturedPawn = state.pawns[capturedPawnId];
+      moveToRegion(capturedPawn, state.regions.board, null);
+    }
+
+    // 移动棋子到目标位置
+    moveToRegion(pawn, state.regions.board, state.regions.board, [toX, toY]);
+  });
+
+  // 交换卡牌
+  await swapCard(game, player, cardName);
+
+  return {
+    from: { x: fromX, y: fromY },
+    to: { x: toX, y: toY },
+    card: cardName,
+    captured: capturedPawnId,
+  };
+}
 
 /**
  * 交换卡牌：将使用的卡牌与备用卡牌交换
  */
-async function handleSwapCard(game: OnitamaGame, player: PlayerType, usedCard: string) {
-    await game.produceAsync(state => {
-        const spareCard = state.spareCard;
-        const usedCardData = state.cards[usedCard];
-        const spareCardData = state.cards[spareCard];
-        
-        // 从玩家手牌中移除使用的卡牌
-        if (player === 'red') {
-            state.redCards = state.redCards.filter(c => c !== usedCard);
-            state.redCards.push(spareCard);
-        } else {
-            state.blackCards = state.blackCards.filter(c => c !== usedCard);
-            state.blackCards.push(spareCard);
-        }
-        
-        // 更新卡牌区域
-        usedCardData.regionId = 'spare';
-        spareCardData.regionId = player;
-        
-        // 更新备用卡牌
-        state.spareCard = usedCard;
-    });
-}
+async function swapCard(
+  game: OnitamaGame,
+  player: PlayerType,
+  usedCard: string,
+) {
+  await game.produceAsync((state) => {
+    const spareCard = state.spareCard;
+    const usedCardData = state.cards[usedCard];
+    const spareCardData = state.cards[spareCard];
 
-const swapCard = registry.register({
-    schema: 'swap-card <player> <card:string>',
-    run: handleSwapCard
-});
+    // 从玩家手牌中移除使用的卡牌
+    if (player === "red") {
+      state.redCards = state.redCards.filter((c) => c !== usedCard);
+      state.redCards.push(spareCard);
+    } else {
+      state.blackCards = state.blackCards.filter((c) => c !== usedCard);
+      state.blackCards.push(spareCard);
+    }
+
+    // 更新卡牌区域
+    usedCardData.regionId = "spare";
+    spareCardData.regionId = player;
+
+    // 更新备用卡牌
+    state.spareCard = usedCard;
+  });
+}
 
 /**
  * 检查占领胜利条件：玩家的师父棋子到达对手的初始位置
  * 红色师父需要到达 (2, 4) - 黑色师父的初始位置
  * 黑色师父需要到达 (2, 0) - 红色师父的初始位置
  */
-async function handleCheckConquestWin(game: OnitamaGame): Promise<PlayerType | null> {
-    const state = game.value;
+async function checkConquestWin(game: OnitamaGame): Promise<PlayerType | null> {
+  const state = game.value;
 
-    // 红色师父到达 (2, 4)（黑色师父的初始位置）
-    const redMaster = state.pawns['red-master'];
-    if (redMaster && redMaster.regionId === 'board' && redMaster.position[0] === 2 && redMaster.position[1] === 4) {
-        return 'red';
-    }
+  // 红色师父到达 (2, 4)（黑色师父的初始位置）
+  const redMaster = state.pawns["red-master"];
+  if (
+    redMaster &&
+    redMaster.regionId === "board" &&
+    redMaster.position[0] === 2 &&
+    redMaster.position[1] === 4
+  ) {
+    return "red";
+  }
 
-    // 黑色师父到达 (2, 0)（红色师父的初始位置）
-    const blackMaster = state.pawns['black-master'];
-    if (blackMaster && blackMaster.regionId === 'board' && blackMaster.position[0] === 2 && blackMaster.position[1] === 0) {
-        return 'black';
-    }
+  // 黑色师父到达 (2, 0)（红色师父的初始位置）
+  const blackMaster = state.pawns["black-master"];
+  if (
+    blackMaster &&
+    blackMaster.regionId === "board" &&
+    blackMaster.position[0] === 2 &&
+    blackMaster.position[1] === 0
+  ) {
+    return "black";
+  }
 
-    return null;
+  return null;
 }
 
-const checkConquestWin = registry.register({
-    schema: 'check-conquest-win',
-    run: handleCheckConquestWin
-});
-
 /**
  * 检查吃掉胜利条件：对手的师父棋子被吃掉（不在棋盘上）
  */
-async function handleCheckCaptureWin(game: OnitamaGame): Promise<PlayerType | null> {
-    const state = game.value;
-    
-    // 红色师父不在棋盘上，黑色获胜
-    const redMaster = state.pawns['red-master'];
-    if (!redMaster || redMaster.regionId !== 'board') {
-        return 'black';
-    }
-    
-    // 黑色师父不在棋盘上，红色获胜
-    const blackMaster = state.pawns['black-master'];
-    if (!blackMaster || blackMaster.regionId !== 'board') {
-        return 'red';
-    }
-    
-    return null;
-}
+async function checkCaptureWin(game: OnitamaGame): Promise<PlayerType | null> {
+  const state = game.value;
 
-const checkCaptureWin = registry.register({
-    schema: 'check-capture-win',
-    run: handleCheckCaptureWin
-});
+  // 红色师父不在棋盘上，黑色获胜
+  const redMaster = state.pawns["red-master"];
+  if (!redMaster || redMaster.regionId !== "board") {
+    return "black";
+  }
+
+  // 黑色师父不在棋盘上，红色获胜
+  const blackMaster = state.pawns["black-master"];
+  if (!blackMaster || blackMaster.regionId !== "board") {
+    return "red";
+  }
+
+  return null;
+}
 
 /**
  * 综合胜利检测
  */
-async function handleCheckWin(game: OnitamaGame): Promise<PlayerType | null> {
-    const conquestWinner = await handleCheckConquestWin(game);
-    if (conquestWinner) {
-        return conquestWinner;
-    }
-    
-    const captureWinner = await handleCheckCaptureWin(game);
-    if (captureWinner) {
-        return captureWinner;
-    }
-    
-    return null;
-}
+async function checkWin(game: OnitamaGame): Promise<PlayerType | null> {
+  const conquestWinner = await checkConquestWin(game);
+  if (conquestWinner) {
+    return conquestWinner;
+  }
 
-const checkWin = registry.register({
-    schema: 'check-win',
-    run: handleCheckWin
-});
+  const captureWinner = await checkCaptureWin(game);
+  if (captureWinner) {
+    return captureWinner;
+  }
+
+  return null;
+}
 
 /**
  * 获取玩家可用的移动
  */
-export function getAvailableMoves(state: OnitamaState, player: PlayerType): Array<{card: string, fromX: number, fromY: number, toX: number, toY: number}> {
-    const moves: Array<{card: string, fromX: number, fromY: number, toX: number, toY: number}> = [];
+export function getAvailableMoves(
+  state: OnitamaState,
+  player: PlayerType,
+): Array<{
+  card: string;
+  fromX: number;
+  fromY: number;
+  toX: number;
+  toY: number;
+}> {
+  const moves: Array<{
+    card: string;
+    fromX: number;
+    fromY: number;
+    toX: number;
+    toY: number;
+  }> = [];
 
-    // 获取玩家的所有卡牌
-    const cardNames = player === 'red' ? state.redCards : state.blackCards;
+  // 获取玩家的所有卡牌
+  const cardNames = player === "red" ? state.redCards : state.blackCards;
 
-    // 获取玩家的所有棋子
-    const playerPawns = Object.values(state.pawns).filter(p => p.owner === player && p.regionId === 'board');
+  // 获取玩家的所有棋子
+  const playerPawns = Object.values(state.pawns).filter(
+    (p) => p.owner === player && p.regionId === "board",
+  );
 
-    // 对于每张卡牌
-    for (const cardName of cardNames) {
-        // 获取旋转后的移动候选项（黑方需要旋转180度）
-        const candidates = getCardMoveCandidates(state, cardName, player);
+  // 对于每张卡牌
+  for (const cardName of cardNames) {
+    // 获取旋转后的移动候选项（黑方需要旋转180度）
+    const candidates = getCardMoveCandidates(state, cardName, player);
 
-        // 对于每个棋子
-        for (const pawn of playerPawns) {
-            const [fromX, fromY] = pawn.position;
+    // 对于每个棋子
+    for (const pawn of playerPawns) {
+      const [fromX, fromY] = pawn.position;
 
-            // 对于卡牌的每个移动
-            for (const move of candidates) {
-                const toX = fromX + move.dx;
-                const toY = fromY + move.dy;
+      // 对于卡牌的每个移动
+      for (const move of candidates) {
+        const toX = fromX + move.dx;
+        const toY = fromY + move.dy;
 
-                // 检查移动是否合法
-                if (isInBounds(toX, toY)) {
-                    const targetPawn = getPawnAtPosition(state, toX, toY);
-                    // 目标位置为空或有敌方棋子
-                    if (!targetPawn || targetPawn.owner !== player) {
-                        moves.push({ card: cardName, fromX, fromY, toX, toY });
-                    }
-                }
-            }
+        // 检查移动是否合法
+        if (isInBounds(toX, toY)) {
+          const targetPawn = getPawnAtPosition(state, toX, toY);
+          // 目标位置为空或有敌方棋子
+          if (!targetPawn || targetPawn.owner !== player) {
+            moves.push({ card: cardName, fromX, fromY, toX, toY });
+          }
         }
+      }
     }
+  }
 
-    return moves;
+  return moves;
 }
 
 /**
  * 处理回合
  */
-async function handleTurn(game: OnitamaGame, turnPlayer: PlayerType) {
-    const state = game.value;
-    const availableMoves = getAvailableMoves(state, turnPlayer);
-    
-    let moveOutput;
-    
-    if (availableMoves.length === 0) {
-        // 没有可用移动，玩家必须交换一张卡牌
-        const cardToSwap = await game.prompt(
-            prompts.move,
-            (player, card, _fromX, _fromY, _toX, _toY) => {
-                if (player !== turnPlayer) {
-                    throw `Invalid player: ${player}. Expected ${turnPlayer}.`;
-                }
-                if (!playerHasCard(state, player, card)) {
-                    throw `Player ${player} does not have card ${card}.`;
-                }
-                return card;
-            },
-            turnPlayer
-        );
-        
-        await swapCard(game, turnPlayer, cardToSwap);
-        moveOutput = { swappedCard: cardToSwap, noMoves: true };
-    } else {
-        // 有可用移动，提示玩家选择
-        moveOutput = await game.prompt(
-            prompts.move,
-            (player, card, fromX, fromY, toX, toY) => {
-                if (player !== turnPlayer) {
-                    throw `Invalid player: ${player}. Expected ${turnPlayer}.`;
-                }
-                
-                const error = isValidMove(state, card, fromX, fromY, toX, toY, player);
-                if (error) {
-                    throw error;
-                }
-                
-                return { player, card, fromX, fromY, toX, toY };
-            },
-            turnPlayer
-        );
-        
-        await move(game, moveOutput.player, moveOutput.card, moveOutput.fromX, moveOutput.fromY, moveOutput.toX, moveOutput.toY);
-    }
-    
-    // 检查胜利
-    const winner = await checkWin(game);
-    
-    await game.produceAsync(state => {
-        state.winner = winner;
-        if (!winner) {
-            state.currentPlayer = state.currentPlayer === 'red' ? 'black' : 'red';
-            state.turn++;
-        }
-    });
-    
-    return { winner, move: moveOutput };
-}
+async function turn(game: OnitamaGame, turnPlayer: PlayerType) {
+  const state = game.value;
+  const availableMoves = getAvailableMoves(state, turnPlayer);
 
-const turn = registry.register({
-    schema: 'turn <player>',
-    run: handleTurn
-});
+  let moveOutput;
+
+  if (availableMoves.length === 0) {
+    // 没有可用移动，玩家必须交换一张卡牌
+    const cardToSwap = await game.prompt(
+      prompts.move,
+      (player, card, _fromX, _fromY, _toX, _toY) => {
+        if (player !== turnPlayer) {
+          throw `Invalid player: ${player}. Expected ${turnPlayer}.`;
+        }
+        if (!playerHasCard(state, player, card)) {
+          throw `Player ${player} does not have card ${card}.`;
+        }
+        return card;
+      },
+      turnPlayer,
+    );
+
+    await swapCard(game, turnPlayer, cardToSwap);
+    moveOutput = { swappedCard: cardToSwap, noMoves: true };
+  } else {
+    // 有可用移动，提示玩家选择
+    moveOutput = await game.prompt(
+      prompts.move,
+      (player, card, fromX, fromY, toX, toY) => {
+        if (player !== turnPlayer) {
+          throw `Invalid player: ${player}. Expected ${turnPlayer}.`;
+        }
+
+        const error = isValidMove(state, card, fromX, fromY, toX, toY, player);
+        if (error) {
+          throw error;
+        }
+
+        return { player, card, fromX, fromY, toX, toY };
+      },
+      turnPlayer,
+    );
+
+    await move(
+      game,
+      moveOutput.player,
+      moveOutput.card,
+      moveOutput.fromX,
+      moveOutput.fromY,
+      moveOutput.toX,
+      moveOutput.toY,
+    );
+  }
+
+  // 检查胜利
+  const winner = await checkWin(game);
+
+  await game.produceAsync((state) => {
+    state.winner = winner;
+    if (!winner) {
+      state.currentPlayer = state.currentPlayer === "red" ? "black" : "red";
+      state.turn++;
+    }
+  });
+
+  return { winner, move: moveOutput };
+}
 
 /**
  * 开始游戏主循环
  */
 export async function start(game: OnitamaGame) {
-    // Initialize cards with RNG at game start
-    initializeCards(game);
+  // Initialize cards with RNG at game start
+  initializeCards(game);
 
-    while (true) {
-        const currentPlayer = game.value.currentPlayer;
-        const turnOutput = await turn(game, currentPlayer);
+  while (true) {
+    const currentPlayer = game.value.currentPlayer;
+    const turnOutput = await turn(game, currentPlayer);
 
-        if (turnOutput.winner) {
-            break;
-        }
+    if (turnOutput.winner) {
+      break;
     }
+  }
 
-    return game.value;
+  return game.value;
 }
diff --git a/src/samples/tic-tac-toe.ts b/src/samples/tic-tac-toe.ts
index 74e78b4..72e91b2 100644
--- a/src/samples/tic-tac-toe.ts
+++ b/src/samples/tic-tac-toe.ts
@@ -1,10 +1,6 @@
 import { Part } from "@/core/part";
 import { createRegion } from "@/core/region";
-import {
-  createGameCommandRegistry,
-  createPromptDef,
-  IGameContext,
-} from "@/core/game";
+import { createPromptDef, IGameContext } from "@/core/game";
 
 const BOARD_SIZE = 3;
 const MAX_TURNS = BOARD_SIZE * BOARD_SIZE;
@@ -69,7 +65,6 @@ export function createInitialState() {
 }
 export type TicTacToeState = ReturnType<typeof createInitialState>;
 export type TicTacToeGame = IGameContext<TicTacToeState>;
-export const registry = createGameCommandRegistry<TicTacToeState>();
 export const prompts = {
   play: createPromptDef<[PlayerType, number, number]>(
     "play <player> <row:number> <col:number>",
@@ -95,34 +90,35 @@ export async function start(game: TicTacToeGame) {
   return game.value;
 }
 
-const turn = registry.register({
-  schema: "turn <player> <turnNumber:number>",
-  async run(game: TicTacToeGame, turnPlayer: PlayerType, turnNumber: number) {
-    const { player, row, col } = await game.prompt(
-      prompts.play,
-      (player, row, col) => {
-        if (player !== turnPlayer) {
-          throw `Invalid player: ${player}. Expected ${turnPlayer}.`;
-        } else if (!isValidMove(row, col)) {
-          throw `Invalid position: (${row}, ${col}). Must be between 0 and ${BOARD_SIZE - 1}.`;
-        } else if (isCellOccupied(game, row, col)) {
-          throw `Cell (${row}, ${col}) is already occupied.`;
-        } else {
-          return { player, row, col };
-        }
-      },
-      game.value.currentPlayer,
-    );
+async function turn(
+  game: TicTacToeGame,
+  turnPlayer: PlayerType,
+  turnNumber: number,
+) {
+  const { player, row, col } = await game.prompt(
+    prompts.play,
+    (player, row, col) => {
+      if (player !== turnPlayer) {
+        throw `Invalid player: ${player}. Expected ${turnPlayer}.`;
+      } else if (!isValidMove(row, col)) {
+        throw `Invalid position: (${row}, ${col}). Must be between 0 and ${BOARD_SIZE - 1}.`;
+      } else if (isCellOccupied(game, row, col)) {
+        throw `Cell (${row}, ${col}) is already occupied.`;
+      } else {
+        return { player, row, col };
+      }
+    },
+    game.value.currentPlayer,
+  );
 
-    placePiece(game, row, col, turnPlayer);
+  placePiece(game, row, col, turnPlayer);
 
-    const winner = checkWinner(game);
-    if (winner) return { winner };
-    if (turnNumber >= MAX_TURNS) return { winner: "draw" as WinnerType };
+  const winner = checkWinner(game);
+  if (winner) return { winner };
+  if (turnNumber >= MAX_TURNS) return { winner: "draw" as WinnerType };
 
-    return { winner: null };
-  },
-});
+  return { winner: null };
+}
 
 function isValidMove(row: number, col: number): boolean {
   return (