     let shieldCategory : UInt32 = 0x1 << 3
     let lifeBarCategory : UInt32 = 0x1 << 4
     var ammo = 5
-
+    var score = 0
+    
     private var mainLayer : SKNode?
     private var menuLayer : SKNode?
     private var cannon : SKSpriteNode?
     private var ammoDisplay : SKSpriteNode?
+    private var scoreLabel : SKLabelNode?
     //private var explosion : SKEmitterNode?
     private var didShoot = false
     

            //self.ammo = ammo
            ammoDisplay?.texture = SKTexture(imageNamed: String.init(format: "Ammo%d", ammo))
        }
    }
    
    func shoot() {

        mainLayer?.removeAllChildren()
        
        ammo = 5
        score = 0
        
        // Add shields
        for i in 0...6 {
