diff --git a/lib/components/player.dart b/lib/components/player.dart
index bef05b8..9906f8f 100644
--- a/lib/components/player.dart
+++ b/lib/components/player.dart
@@ -1,11 +1,12 @@
 import 'package:flame/components.dart';
-import '../utility/direction.dart';
 import 'package:flame/sprite.dart';
 
+import '../utility/direction.dart';
+
 class Player extends SpriteAnimationComponent with HasGameRef {
   final double _playerSpeed = 300.0;
   final double _animationSpeed = 0.15;
-  final double _moveCoordinate = 4;
+  final double _moveCoordinate = 8;
   int _moveCount = 0;
 
   late final SpriteAnimation _runDownAnimation;
@@ -18,8 +19,8 @@ class Player extends SpriteAnimationComponent with HasGameRef {
 
   Player()
       : super(
-    size: Vector2.all(64.0),
-  );
+          size: Vector2.all(64.0),
+        );
 
   @override
   Future<void> onLoad() async {
@@ -91,4 +92,4 @@ class Player extends SpriteAnimationComponent with HasGameRef {
     _moveCount -= _moveCoordinate as int;
     position.add(vac);
   }
-}
\ No newline at end of file
+}
diff --git a/lib/game.dart b/lib/game.dart
index 53061b4..c3b9008 100644
--- a/lib/game.dart
+++ b/lib/game.dart
@@ -1,12 +1,12 @@
 import 'package:flame/components.dart';
-import 'package:flutter/services.dart';
-import 'package:flutter/cupertino.dart';
 import 'package:flame/game.dart';
 import 'package:flame/input.dart';
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/services.dart';
 
-import 'utility/direction.dart';
-import 'src/push_game.dart';
 import 'components/player.dart';
+import 'src/push_game.dart';
+import 'utility/direction.dart';
 
 class MainGame extends FlameGame with KeyboardEvents, HasGameRef {
   PushGame pushGame = PushGame();
@@ -57,24 +57,30 @@ class MainGame extends FlameGame with KeyboardEvents, HasGameRef {
   }
 
   @override
-  KeyEventResult onKeyEvent(RawKeyEvent event, Set<LogicalKeyboardKey> keysPressed) {
+  KeyEventResult onKeyEvent(
+      RawKeyEvent event, Set<LogicalKeyboardKey> keysPressed) {
     final isKeyDown = event is RawKeyDownEvent;
     Direction keyDirection = Direction.none;
 
-    if (!isKeyDown || _player.moveCount != 0) return super.onKeyEvent(event, keysPressed);
+    if (!isKeyDown || _player.moveCount != 0)
+      return super.onKeyEvent(event, keysPressed);
 
-    if (event.logicalKey == LogicalKeyboardKey.keyA || event.logicalKey == LogicalKeyboardKey.arrowLeft) {
+    if (event.logicalKey == LogicalKeyboardKey.keyA ||
+        event.logicalKey == LogicalKeyboardKey.arrowLeft) {
       keyDirection = Direction.left;
-    } else if (event.logicalKey == LogicalKeyboardKey.keyD || event.logicalKey == LogicalKeyboardKey.arrowRight) {
+    } else if (event.logicalKey == LogicalKeyboardKey.keyD ||
+        event.logicalKey == LogicalKeyboardKey.arrowRight) {
       keyDirection = Direction.right;
-    } else if (event.logicalKey == LogicalKeyboardKey.keyW || event.logicalKey == LogicalKeyboardKey.arrowUp) {
+    } else if (event.logicalKey == LogicalKeyboardKey.keyW ||
+        event.logicalKey == LogicalKeyboardKey.arrowUp) {
       keyDirection = Direction.up;
-    } else if (event.logicalKey == LogicalKeyboardKey.keyS || event.logicalKey == LogicalKeyboardKey.arrowDown) {
+    } else if (event.logicalKey == LogicalKeyboardKey.keyS ||
+        event.logicalKey == LogicalKeyboardKey.arrowDown) {
       keyDirection = Direction.down;
     }
 
-    pushGame.update(keyDirection.name);
-    playerMove(isKeyDown, keyDirection);
+    bool isMove = pushGame.changeState(keyDirection.name);
+    if (isMove) playerMove(isKeyDown, keyDirection);
 
     return super.onKeyEvent(event, keysPressed);
   }
diff --git a/lib/src/push_game.dart b/lib/src/push_game.dart
index 5038a34..8fae4fa 100644
--- a/lib/src/push_game.dart
+++ b/lib/src/push_game.dart
@@ -15,7 +15,8 @@ class PushGame {
   }
 
   List<Object> get initStageState {
-    final List<Object>stageStateList = List<Object>.filled(stageWidth * stageHeight, Object.unknown);
+    final List<Object> stageStateList =
+        List<Object>.filled(stageWidth * stageHeight, Object.unknown);
     int x, y;
     x = y = 0;
 
@@ -23,14 +24,30 @@ class PushGame {
       for (var rune in dataX.runes) {
         final Object t;
         switch (String.fromCharCode(rune)) {
-          case '#': t = Object.wall; break;
-          case ' ': t = Object.space; break;
-          case 'o': t = Object.block; break;
-          case 'O': t = Object.blockOnGoal; break;
-          case '.': t = Object.goal; break;
-          case 'p': t = Object.man; break;
-          case 'P': t = Object.manOnGoal; break;
-          default: t = Object.unknown; break;
+          case '#':
+            t = Object.wall;
+            break;
+          case ' ':
+            t = Object.space;
+            break;
+          case 'o':
+            t = Object.block;
+            break;
+          case 'O':
+            t = Object.blockOnGoal;
+            break;
+          case '.':
+            t = Object.goal;
+            break;
+          case 'p':
+            t = Object.man;
+            break;
+          case 'P':
+            t = Object.manOnGoal;
+            break;
+          default:
+            t = Object.unknown;
+            break;
         }
         if (t != Object.unknown) {
           stageStateList[y * stageWidth + x] = t;
@@ -43,17 +60,26 @@ class PushGame {
     return stageStateList;
   }
 
-  int get playerIndex => stageState.indexWhere((obj) => obj == Object.man || obj == Object.manOnGoal);
+  int get playerIndex => stageState
+      .indexWhere((obj) => obj == Object.man || obj == Object.manOnGoal);
 
   Map<String, int> getMoveDirection(String input) {
     int dx, dy;
     dx = dy = 0;
 
     switch (input) {
-      case 'left': dx = -1; break;
-      case 'right': dx = 1; break;
-      case 'up': dy = -1; break;
-      case 'down': dy = 1; break;
+      case 'left':
+        dx = -1;
+        break;
+      case 'right':
+        dx = 1;
+        break;
+      case 'up':
+        dy = -1;
+        break;
+      case 'down':
+        dy = 1;
+        break;
     }
     return {
       'dx': dx,
@@ -61,16 +87,20 @@ class PushGame {
     };
   }
 
-  bool isCoordinate(tx, ty) => tx < 0 || ty < 0 || tx >= stageWidth || ty >= stageHeight;
+  bool isWorldOut(tx, ty) =>
+      tx < 0 || ty < 0 || tx >= stageWidth || ty >= stageHeight;
 
-  bool isMoveObject(int targetPosition) => stageState[targetPosition] == Object.space || stageState[targetPosition] == Object.goal;
+  bool isMoveObject(int targetPosition) =>
+      stageState[targetPosition] == Object.space ||
+      stageState[targetPosition] == Object.goal;
 
   bool get isClear => stageState.indexWhere((obj) => obj == Object.block) == -1;
 
-  Map<String, int> get playerVecPos => { 'x': playerIndex % stageWidth, 'y': playerIndex ~/ stageWidth };
+  Map<String, int> get playerVecPos =>
+      {'x': playerIndex % stageWidth, 'y': playerIndex ~/ stageWidth};
 
   List<String> get splitStageStateList {
-    final List<String>stageStateList = List<String>.filled(stageHeight, '');
+    final List<String> stageStateList = List<String>.filled(stageHeight, '');
 
     for (int y = 0; y < stageHeight; ++y) {
       String line = '';
@@ -97,43 +127,53 @@ class PushGame {
     }
   }
 
-  void changeState(String input) {
+  bool changeState(String input) {
     int? dx = getMoveDirection(input)['dx'];
     int? dy = getMoveDirection(input)['dy'];
     int? x = playerVecPos['x']; // modulus operator
     int? y = playerVecPos['y']; // integer division operator
-
     // post move coordinate
     int tx = x! + dx!;
     int ty = y! + dy!;
-
     // Maximum and minimum coordinate checks
-    if (isCoordinate(tx, ty)) return;
+    if (isWorldOut(tx, ty)) return false;
 
     int p = y * stageWidth + x; // PlayerPosition
     int tp = ty * stageWidth + tx; // TargetPosition
 
     if (isMoveObject(tp)) {
-      stageState[tp] = (stageState[tp] == Object.goal) ? Object.manOnGoal : Object.man;
-      stageState[p] = (stageState[p] == Object.manOnGoal) ? Object.goal : Object.space;
+      stageState[tp] =
+          (stageState[tp] == Object.goal) ? Object.manOnGoal : Object.man;
+      stageState[p] =
+          (stageState[p] == Object.manOnGoal) ? Object.goal : Object.space;
     }
     // Blank or goal. People move.
-    else if (stageState[tp] == Object.block || stageState[tp] == Object.blockOnGoal) {
+    else if (stageState[tp] == Object.block ||
+        stageState[tp] == Object.blockOnGoal) {
       // So two squares away is in range.
       int tx2 = tx + dx;
       int ty2 = ty + dy;
 
-      if (tx2 < 0 || ty2 < 0 || tx2 >= stageWidth || ty2 >= stageHeight) { // Impossible to push.
-        return;
+      if (tx2 < 0 || ty2 < 0 || tx2 >= stageWidth || ty2 >= stageHeight) {
+        // Impossible to push.
+        return false;
       }
 
       int tp2 = (ty + dy) * stageWidth + (tx + dx); // two squares away
       if (stageState[tp2] == Object.space || stageState[tp2] == Object.goal) {
         // sequential replacement
-        stageState[tp2] = (stageState[tp2] == Object.goal) ? Object.blockOnGoal : Object.block;
-        stageState[tp] = (stageState[tp] == Object.blockOnGoal) ? Object.manOnGoal : Object.man;
-        stageState[p] = (stageState[p] == Object.manOnGoal ) ? Object.goal : Object.space;
+        stageState[tp2] = (stageState[tp2] == Object.goal)
+            ? Object.blockOnGoal
+            : Object.block;
+        stageState[tp] = (stageState[tp] == Object.blockOnGoal)
+            ? Object.manOnGoal
+            : Object.man;
+        stageState[p] =
+            (stageState[p] == Object.manOnGoal) ? Object.goal : Object.space;
       }
+    } else {
+      return false;
     }
+    return true;
   }
 }