void OnTriggerEnter2D(Collider2D coll)
    {
        EnemyProjectile missile = coll.GetComponent <EnemyProjectile> ();

        if (missile)
        {
            print("hit by a projectile");
            missile.Hit();
            health -= missile.Damage();
            if (health <= 0)
            {
                scoreKeeper.Die();
                AudioSource.PlayClipAtPoint(playerDeadAudioClip, this.transform.position);
                LevelManager lm = GameObject.Find("LevelManager").GetComponent <LevelManager> ();
                lm.loadLevel("Scenes/Win");
                Destroy(gameObject);
            }
        }
    }