Simple games by using Buttons and Labels

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Button_Game
{
    public partial class Form1 : Form
    {
        int flag, i = 0;
        public Form1()
        {
         InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            button1.Visible = false;
            button2.Visible = false;
            button3.Visible = false;
            button4.Visible = false;
            button5.Visible = false;
            button6.Visible = false;
            button7.Visible = false;
            button8.Visible = false;
            button9.Visible = false;
            label2.Text = i.ToString();
        }
        private void timer1_Tick(object sender, EventArgs e)
        {    Random random = new Random();
            int randomno = random.Next(1, 10);
            if (randomno == 1)
            {
                flag = 1;
                button1.Visible = true;

                timer1.Enabled = false;
                timer2.Enabled = true;
            }
           else if (randomno == 2)
            {
                flag = 2;
                button2.Visible = true;

                timer1.Enabled = false;
                timer2.Enabled = true;
            }
            else if (randomno == 3)
            {
                flag = 3;
                button3.Visible = true;
                timer1.Enabled = false;
                timer2.Enabled = true;
            }
            else if (randomno == 4)
            {
                flag = 4;
                button4.Visible = true;

                timer1.Enabled = false;
                timer2.Enabled = true;
            }
            else if (randomno == 5)
            {
                flag = 5;
                button5.Visible = true;

                timer1.Enabled = false;
                timer2.Enabled = true;
            }
            else if (randomno == 6)
            {
                flag = 6;
                button6.Visible = true;

                timer1.Enabled = false;
                timer2.Enabled = true;
            }
            else if (randomno == 7)
            {
                flag = 7;
                button7.Visible = true;

                timer1.Enabled = false;
                timer2.Enabled = true;
            }
            else if (randomno == 8)
            {
                flag = 8;
                button8.Visible = true;
                timer1.Enabled = false;
                timer2.Enabled = true;
            }
            else if (randomno == 9)
            {
                flag = 9;
                button9.Visible = true;

                timer1.Enabled = false;
                timer2.Enabled = true;
            }
        }
        private void timer2_Tick(object sender, EventArgs e)
        {
            if (flag == 1)
            {
                button1.Visible = false;
                timer2.Enabled = false;
                timer1.Enabled = true;
            }
            else if (flag == 2)
            {
                button2.Visible = false;
                timer2.Enabled = false;
                timer1.Enabled = true;
            }
            else if (flag == 3)
            {
                button3.Visible = false;
                timer2.Enabled = false;
                timer1.Enabled = true;
            }
            else if (flag == 4)
            {
                button4.Visible = false;
                timer2.Enabled = false;
                timer1.Enabled = true;
            }
            else if (flag == 5)
            {
                button5.Visible = false;
                timer2.Enabled = false;
                timer1.Enabled = true;
            }
            else if (flag == 6)
            {
                button6.Visible = false;
                timer2.Enabled = false;
                timer1.Enabled = true;
            }
            else if (flag == 7)
            {
                button7.Visible = false;
                timer2.Enabled = false;
                timer1.Enabled = true;
            }
            else if (flag == 8)
            {
                button8.Visible = false;
                timer2.Enabled = false;
                timer1.Enabled = true;
            }
            else if (flag == 9)
            {
                button9.Visible = false;
                timer2.Enabled = false;
                timer1.Enabled = true;
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            label2.Text = (i++).ToString();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            label2.Text = (i++).ToString();
        }
        private void button3_Click(object sender, EventArgs e)
        {
            label2.Text = (i++).ToString();
        }
        private void button4_Click(object sender, EventArgs e)
        {
            label2.Text = (i++).ToString();
        }
        private void button5_Click(object sender, EventArgs e)
        {
            label2.Text = (i++).ToString();
        }
        private void button6_Click(object sender, EventArgs e)
        {
            label2.Text = (i++).ToString();
        }
        private void button7_Click(object sender, EventArgs e)
        {
            label2.Text = (i++).ToString();
        }
        private void button8_Click(object sender, EventArgs e)
        {
            label2.Text = (i++).ToString();
        }
        private void button9_Click(object sender, EventArgs e)
        {
            label2.Text = (i++).ToString();
        }
        private void button10_Click(object sender, EventArgs e)
        {
            timer1.Enabled = true;
        }
        private void button11_Click(object sender, EventArgs e)
        {
            timer1.Enabled = false;
            timer2.Enabled = false;
            button1.Visible = false;
            button2.Visible = false;
            button3.Visible = false;
            button4.Visible = false;
            button5.Visible = false;
            button6.Visible = false;
            button7.Visible = false;
            button8.Visible = false;
            button9.Visible = false;
            i = 0;
            label2.Text = i.ToString();
        }
        private void button12_Click(object sender, EventArgs e)
        {
            MessageBox.Show("  JUST CLICK ON BOXES BEFORE THEY DISAPPEAR AND IF CLICKED YOU GET A +1 SCORE");
        }

        private void button13_Click(object sender, EventArgs e)
        {
            MessageBox.Show("Quick Reaction 1.0, This is my First Window app created in visual c#");
        }
      }
}