private void btn_medium_Click(object sender, EventArgs e)
        {
            this.Hide();
            MatchingGame mg = new MatchingGame();

            mg.Show();
            mg.gameTimer.Interval = 600;
            mg.timer          = 75;
            mg.lbl_timer.Text = "75 seconds";
            mg.timeElpased.Start();
        }
        private void btn_sprHard_Click(object sender, EventArgs e)
        {
            this.Hide();
            MatchingGame mg = new MatchingGame();

            mg.Show();
            mg.gameTimer.Interval = 400;
            mg.timer          = 30;
            mg.lbl_timer.Text = "30 seconds";
            mg.timeElpased.Start();
        }
        public void btn_sprEasy_Click(object sender, EventArgs e)
        {
            this.Hide();
            MatchingGame mg = new MatchingGame();

            mg.Show();
            mg.gameTimer.Interval = 800;
            mg.timer          = 95;
            mg.lbl_timer.Text = "95 seconds";
            mg.timeElpased.Start();
        }