Hi Marc, great tutorial! One small mistake I guess: when you define the floorNode’s physicsBody you make it to wide on the right (you forgot to divide the size.width by 2). It should be:
floorNode.physicsBody = SKPhysicsBody(edgeFrom: CGPoint(x: -size.width / 2, y: 0), to: CGPoint(x: size.width / 2, y: 0))