===================================================================
--- original.js
+++ change.js
@@ -71,8 +71,39 @@
 	self.updateScore = function (newScore) {
 		scoreText.setText(newScore.toString());
 	};
 });
+// Upgrade class
+var Upgrade = Container.expand(function () {
+	var self = Container.call(this);
+	var upgradeGraphics = self.createAsset('upgrade', 'Clickable upgrade', 0.5, 0.5);
+	self.cost = 10; // Initial cost of the upgrade
+	self.multiplier = 1; // Score multiplier
+	self.updateCost = function () {
+		self.cost *= 2; // Double the cost for the next upgrade
+	};
+	self.increaseMultiplier = function () {
+		self.multiplier += 1; // Increase the multiplier by 1
+	};
+	var upgradeText = new Text2('Upgrade: $' + self.cost, {
+		size: 100,
+		fill: "#ffffff"
+	});
+	upgradeText.anchor.set(0.5, 0);
+	self.addChild(upgradeText);
+	self.updateUpgradeText = function () {
+		upgradeText.setText('Upgrade: $' + self.cost);
+	};
+	self.onClick = function () {
+		if (currentScore >= self.cost) {
+			currentScore -= self.cost; // Deduct the cost from the current score
+			score.updateScore(currentScore); // Update the score display
+			self.updateCost(); // Update the cost for the next upgrade
+			self.increaseMultiplier(); // Increase the score multiplier
+			self.updateUpgradeText(); // Update the upgrade text
+		}
+	};
+});
 
 /**** 
 * Initialize Game
 ****/
@@ -94,12 +125,18 @@
 // Initialize game variables
 var currentScore = 0;
 // Update the score when the pizza is clicked
 pizza.onClick = function () {
-	currentScore += 1; // Increment score by $1 per click
+	currentScore += upgrade.multiplier; // Increment score by the upgrade multiplier per click
 	score.updateScore(currentScore);
-};
-// Add event listener for pizza clicks
+}; // Initialize upgrade
+var upgrade = game.addChild(new Upgrade());
+upgrade.x = 2048 / 2;
+upgrade.y = 2732 - 300; // Position upgrade button at the bottom center
+// Add event listener for upgrade clicks
+upgrade.on('down', function (obj) {
+	upgrade.onClick();
+});
 pizza.on('down', function (obj) {
 	pizza.onClick();
 });
 // Main game tick event