===================================================================
--- original.js
+++ change.js
@@ -90,8 +90,18 @@
 
 /**** 
 * Game Code
 ****/ 
+// Initialize score
+var score = 0;
+// Initialize score text
+var scoreTxt = new Text2(score.toString(), {
+	size: 50,
+	fill: "#ffffff"
+});
+scoreTxt.x = 20;
+scoreTxt.y = 20;
+LK.gui.top.addChild(scoreTxt);
 var fighterJet = game.addChild(new FighterJet());
 fighterJet.x = 2048 / 2;
 fighterJet.y = 2732 - 200;
 var heroMissiles = [];
@@ -144,8 +154,11 @@
 				// Add explosion effect for heroMissile
 				LK.effects.flashObject(heroMissile, 0xff0000, 1000);
 				heroMissile.destroy();
 				heroMissiles.splice(heroMissiles.indexOf(heroMissile), 1);
+				// Update score
+				score += 150;
+				scoreTxt.setText(score.toString());
 			}
 		});
 		enemyMissiles.forEach(function (enemyMissile) {
 			if (heroMissile.intersects(enemyMissile)) {
@@ -155,8 +168,11 @@
 				// Add explosion effect for heroMissile
 				LK.effects.flashObject(heroMissile, 0xff0000, 1000);
 				heroMissile.destroy();
 				heroMissiles.splice(heroMissiles.indexOf(heroMissile), 1);
+				// Update score
+				score += 50;
+				scoreTxt.setText(score.toString());
 			}
 		});
 	});
 	// Spawn new aliens