var AI = function () {
	this.makeMove = function (board) {};
};
var Tile = Container.expand(function () {
	var self = Container.call(this);
	var tileGraphics = self.createAsset('tile', 'Game Tile', .5, .5);
	self.state = 'empty';
	self.flip = function (newState) {
		self.state = newState;
		if (self.state === 'black') {
			self.createAsset('blackTile', 'Black Tile', .5, .5);
		} else if (self.state === 'white') {
			self.createAsset('whiteTile', 'White Tile', .5, .5);
		}
	};
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	function flipTiles(board, color, x, y) {
		var opponent = color === 'black' ? 'white' : 'black';
		var directions = [{
			x: -1,
			y: 0
		}, {
			x: 1,
			y: 0
		}, {
			x: 0,
			y: -1
		}, {
			x: 0,
			y: 1
		}, {
			x: -1,
			y: -1
		}, {
			x: 1,
			y: 1
		}, {
			x: -1,
			y: 1
		}, {
			x: 1,
			y: -1
		}];
		directions.forEach(function (dir) {
			var tilesToFlip = [];
			var xIter = x + dir.x;
			var yIter = y + dir.y;
			while (xIter >= 0 && xIter < 8 && yIter >= 0 && yIter < 8 && board[xIter][yIter].state === opponent) {
				tilesToFlip.push(board[xIter][yIter]);
				xIter += dir.x;
				yIter += dir.y;
			}
			if (xIter >= 0 && xIter < 8 && yIter >= 0 && yIter < 8 && board[xIter][yIter].state === color) {
				tilesToFlip.forEach(function (tile) {
					tile.flip(color);
				});
			}
		});
	}
	function isValidMove(board, color, x, y) {
		var opponent = color === 'black' ? 'white' : 'black';
		var directions = [{
			x: -1,
			y: 0
		}, {
			x: 1,
			y: 0
		}, {
			x: 0,
			y: -1
		}, {
			x: 0,
			y: 1
		}, {
			x: -1,
			y: -1
		}, {
			x: 1,
			y: 1
		}, {
			x: -1,
			y: 1
		}, {
			x: 1,
			y: -1
		}];
		for (var i = 0; i < directions.length; i++) {
			var dir = directions[i];
			var xIter = x + dir.x;
			var yIter = y + dir.y;
			var foundOpponent = false;
			while (xIter >= 0 && xIter < 8 && yIter >= 0 && yIter < 8) {
				if (board[xIter][yIter].state === opponent) {
					foundOpponent = true;
					xIter += dir.x;
					yIter += dir.y;
				} else if (board[xIter][yIter].state === color && foundOpponent) {
					return true;
				} else {
					break;
				}
			}
		}
		return false;
	}
	var board = [];
	var ai = new AI();
	var playerTurn = 'black';
	var tile = new Tile();
	var boardWidth = 8 * tile.width;
	var boardHeight = 8 * tile.height;
	var boardStartX = (2048 - boardWidth) / 2;
	var boardStartY = (2732 - boardHeight) / 2;
	for (var i = 0; i < 8; i++) {
		board[i] = [];
		for (var j = 0; j < 8; j++) {
			var tile = self.addChild(new Tile());
			tile.x = boardStartX + i * tile.width;
			tile.y = boardStartY + j * tile.height;
			board[i][j] = tile;
			tile.on('down', (function (tile, i, j) {
				return function (obj) {
					if (playerTurn === 'black' && tile.state === 'empty' && isValidMove(board, 'black', i, j)) {
						tile.flip('black');
						flipTiles(board, 'black', i, j);
						playerTurn = 'white';
						ai.makeMove(board);
					}
				};
			})(tile, i, j));
		}
	}
	board[3][3].flip('white');
	board[3][4].flip('black');
	board[4][3].flip('black');
	board[4][4].flip('white');
	ai.makeMove(board);
	LK.on('tick', function () {});
});

===================================================================
--- original.js
+++ change.js
@@ -15,8 +15,97 @@
 	};
 });
 var Game = Container.expand(function () {
 	var self = Container.call(this);
+	function flipTiles(board, color, x, y) {
+		var opponent = color === 'black' ? 'white' : 'black';
+		var directions = [{
+			x: -1,
+			y: 0
+		}, {
+			x: 1,
+			y: 0
+		}, {
+			x: 0,
+			y: -1
+		}, {
+			x: 0,
+			y: 1
+		}, {
+			x: -1,
+			y: -1
+		}, {
+			x: 1,
+			y: 1
+		}, {
+			x: -1,
+			y: 1
+		}, {
+			x: 1,
+			y: -1
+		}];
+		directions.forEach(function (dir) {
+			var tilesToFlip = [];
+			var xIter = x + dir.x;
+			var yIter = y + dir.y;
+			while (xIter >= 0 && xIter < 8 && yIter >= 0 && yIter < 8 && board[xIter][yIter].state === opponent) {
+				tilesToFlip.push(board[xIter][yIter]);
+				xIter += dir.x;
+				yIter += dir.y;
+			}
+			if (xIter >= 0 && xIter < 8 && yIter >= 0 && yIter < 8 && board[xIter][yIter].state === color) {
+				tilesToFlip.forEach(function (tile) {
+					tile.flip(color);
+				});
+			}
+		});
+	}
+	function isValidMove(board, color, x, y) {
+		var opponent = color === 'black' ? 'white' : 'black';
+		var directions = [{
+			x: -1,
+			y: 0
+		}, {
+			x: 1,
+			y: 0
+		}, {
+			x: 0,
+			y: -1
+		}, {
+			x: 0,
+			y: 1
+		}, {
+			x: -1,
+			y: -1
+		}, {
+			x: 1,
+			y: 1
+		}, {
+			x: -1,
+			y: 1
+		}, {
+			x: 1,
+			y: -1
+		}];
+		for (var i = 0; i < directions.length; i++) {
+			var dir = directions[i];
+			var xIter = x + dir.x;
+			var yIter = y + dir.y;
+			var foundOpponent = false;
+			while (xIter >= 0 && xIter < 8 && yIter >= 0 && yIter < 8) {
+				if (board[xIter][yIter].state === opponent) {
+					foundOpponent = true;
+					xIter += dir.x;
+					yIter += dir.y;
+				} else if (board[xIter][yIter].state === color && foundOpponent) {
+					return true;
+				} else {
+					break;
+				}
+			}
+		}
+		return false;
+	}
 	var board = [];
 	var ai = new AI();
 	var playerTurn = 'black';
 	var tile = new Tile();
@@ -30,17 +119,18 @@
 			var tile = self.addChild(new Tile());
 			tile.x = boardStartX + i * tile.width;
 			tile.y = boardStartY + j * tile.height;
 			board[i][j] = tile;
-			tile.on('down', (function (tile) {
+			tile.on('down', (function (tile, i, j) {
 				return function (obj) {
-					if (playerTurn === 'black' && tile.state === 'empty') {
+					if (playerTurn === 'black' && tile.state === 'empty' && isValidMove(board, 'black', i, j)) {
 						tile.flip('black');
+						flipTiles(board, 'black', i, j);
 						playerTurn = 'white';
 						ai.makeMove(board);
 					}
 				};
-			})(tile));
+			})(tile, i, j));
 		}
 	}
 	board[3][3].flip('white');
 	board[3][4].flip('black');