===================================================================
--- original.js
+++ change.js
@@ -5,22 +5,26 @@
 	self.pop = function () {};
 });
 var Game = Container.expand(function () {
 	var self = Container.call(this);
-	var bubbles = [];
+	var bubbles = new Array(9).fill().map(() => new Array(9).fill(null));
 	var spawnBubble = function () {
 		for (var i = 0; i < 9; i++) {
 			for (var j = 0; j < 9; j++) {
 				var newBubble = new Bubble();
 				newBubble.x = i * newBubble.width;
 				newBubble.y = j * newBubble.height;
-				bubbles.push(newBubble);
+				bubbles[i][j] = newBubble;
 				self.addChild(newBubble);
 			}
 		}
 	};
 	LK.on('tick', function () {
 		for (var i = 0; i < bubbles.length; i++) {
-			bubbles[i].move();
+			for (var j = 0; j < bubbles[i].length; j++) {
+				if (bubbles[i][j]) {
+					bubbles[i][j].move();
+				}
+			}
 		}
 	});
 });