protected override void Update(GameTime gameTime)
        {
            player.Update(gameTime);

            spawn += (float)gameTime.ElapsedGameTime.TotalSeconds;

            foreach(Zombies zombie in zombies)
                zombie.Update(graphics.GraphicsDevice);
            SpawnZombies();


            if (Keyboard.GetState().IsKeyDown(Keys.Space))
                Shoot();

            UpdateBullets();
            base.Update(gameTime);
        }

        // Bullet Update Method
        public void UpdateBullets()
        {
            foreach (Bullets bullet in bullets)
            {
                bullet.position += bullet.velocity;
                if (Vector2.Distance(bullet.position, player.playerLocation) > 500)
                    bullet.isVisible = false;
            }
            for (int b = 0; b < bullets.Count; b++)
            {
                if (!bullets[b].isVisible)
                {
                    bullets.RemoveAt(b);
                    b--;
                }
            }
        }




----- BULLETS CLASS -----

    class Bullets
    {
        public Texture2D texture;
        public Vector2 position;
        public Vector2 velocity;
        public Vector2 origin;

        public bool isVisible;

        public Bullets(Texture2D newTexture)
        {
            texture = newTexture;
            isVisible = false;
        }



        public void Draw(SpriteBatch spriteBatch)
        {
            spriteBatch.Draw(texture, position,null, Color.White, 0f, origin, 1f, SpriteEffects.None, 0);
        }
    }
}