private void OnCollisionEnter2D(Collision2D collision)
    {
        if (collision.collider.gameObject.tag == "Enemy")
        {
            AudioSource audioSource = gameObject.GetComponent <AudioSource>();
            audioSource.Play();

            if (health > 0)
            {
                health -= 10;
            }


            if (health <= 0)
            {
                health = 0;
                alive  = false;
                gameObject.GetComponent <SpriteRenderer>().sprite = deathSprite;
                audioSource.mute = true;
                this.enabled     = false;
                gameState.GameOver();
            }
        }
    }