var Nutcracker = Container.expand(function () {
	var self = Container.call(this);
	var nutcrackerGraphics = self.createAsset('nutcracker', 'Nutcracker Graphics', .5, .5);
	self.move = function (yLevels) {
		if (!yLevels.includes(self.y)) {
			self.y += 5;
			if (yLevels.some(function (level) {
				return self.y >= level;
			})) {
				self.y = yLevels.find(function (level) {
					return self.y >= level;
				});
			}
		}
	};
	self.attack = function () {};
});
var MouseTrap = Container.expand(function () {
	var self = Container.call(this);
	var mousetrapGraphics = self.createAsset('mousetrap', 'Mouse Trap Graphics', .5, .5);
	self.activate = function () {};
});
var Mouse = Container.expand(function () {
	var self = Container.call(this);
	var mouseGraphics = self.createAsset('mouse', 'Mouse Graphics', .5, .5);
	self.move = function () {
		self.x += 2;
	};
	self.attack = function () {};
});
var BuildingMenu = Container.expand(function () {
	var self = Container.call(this);
	self.y = 0;
	self.x = 0;
	var menuBackground = self.createAsset('menuBackground', 'Building Menu Background', 0.5, 0);
	self.addChild(menuBackground);
});
var NutcrackerButton = Container.expand(function () {
	var self = Container.call(this);
	var buttonGraphics = self.createAsset('nutcrackerButton', 'Nutcracker Build Button', 0.5, 0);
	var dragObject = null;
	self.addChild(buttonGraphics);
	self.y = 200;
	self.on('down', function (obj) {
		dragObject = new Nutcracker();
		self.addChild(dragObject);
		var pos = obj.event.getLocalPosition(self.parent);
		dragObject.x = pos.x;
		dragObject.y = pos.y;
	});
	stage.on('up', function (obj) {
		var pos = obj.event.getLocalPosition(self);
		if (dragObject) {
			if (pos.y > 300) {
				var newNutcracker = new Nutcracker();
				newNutcracker.x = pos.x;
				newNutcracker.y = pos.y;
				self.addChild(newNutcracker);
				self.removeChild(dragObject);
				dragObject = null;
			} else {
				self.removeChild(dragObject);
				dragObject = null;
			}
		}
	});
	stage.on('move', function (obj) {
		if (dragObject) {
			var pos = obj.event.getLocalPosition(self);
			dragObject.x = pos.x;
			dragObject.y = pos.y;
		}
	});
});
var Game = Container.expand(function () {
	var self = Container.call(this);
	var background = self.createAsset('background', 'Background Graphics', 0, 0);
	self.addChildAt(background, 0);
	var buildingMenu = self.addChild(new BuildingMenu());
	LK.gui.topCenter.addChild(buildingMenu);
	var nutcrackers = [];
	var mousetraps = [];
	var mice = [];
	var nutcrackerButton = self.addChild(new NutcrackerButton());
	LK.gui.topCenter.addChild(nutcrackerButton);
	var tickCounter = 0;
	var yLevels = [2500, 2200, 1900];
	LK.on('tick', function () {
		tickCounter++;
		if (tickCounter % 600 == 0) {
			var newMouse = new Mouse();
			newMouse.x = 0 - newMouse.width;
			newMouse.y = yLevels[Math.floor(Math.random() * yLevels.length)];
			mice.push(newMouse);
			self.addChild(newMouse);
		}
		for (var i = 0; i < nutcrackers.length; i++) {
			nutcrackers[i].move();
			nutcrackers[i].attack();
		}
		for (var i = 0; i < mousetraps.length; i++) {
			mousetraps[i].activate();
		}
		for (var i = mice.length - 1; i >= 0; i--) {
			mice[i].move();
			mice[i].attack();
			if (mice[i].x > 2048 + mice[i].width) {
				mice[i].destroy();
				mice.splice(i, 1);
			}
		}
	});
});

===================================================================
--- original.js
+++ change.js
@@ -1,8 +1,19 @@
 var Nutcracker = Container.expand(function () {
 	var self = Container.call(this);
 	var nutcrackerGraphics = self.createAsset('nutcracker', 'Nutcracker Graphics', .5, .5);
-	self.move = function () {};
+	self.move = function (yLevels) {
+		if (!yLevels.includes(self.y)) {
+			self.y += 5;
+			if (yLevels.some(function (level) {
+				return self.y >= level;
+			})) {
+				self.y = yLevels.find(function (level) {
+					return self.y >= level;
+				});
+			}
+		}
+	};
 	self.attack = function () {};
 });
 var MouseTrap = Container.expand(function () {
 	var self = Container.call(this);