Notes

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;
namespace WindowsFormsApp1
{

public partial class Form1 : Form
{
enum PlayerTurn { None, Player1, Player2};
enum Winner { None, Player1, Player2, Draw};

PlayerTurn turn;
Winner winner;
void OnNewGame()
{
PictureBox[] allPictures = {pictureBox0,
pictureBox1,
pictureBox2,
pictureBox3,
pictureBox4,
pictureBox5,
pictureBox6,
pictureBox7,
pictureBox8,};

//Clear all Game board cells;
foreach (var p in allPictures)
p.Image = null;

turn = PlayerTurn.Player1;
winner = Winner.None;
ShowTurn();

}

Winner GetWinner()
{
PictureBox[] allWinningMoves= {
//Row
pictureBox0, pictureBox1, pictureBox2,
pictureBox3, pictureBox4, pictureBox5,
pictureBox6, pictureBox7, pictureBox8,
//Columns
pictureBox0, pictureBox3, pictureBox6,
pictureBox1, pictureBox4, pictureBox7,
pictureBox2, pictureBox5, pictureBox8,
//Diagonal
pictureBox0, pictureBox4, pictureBox8,
pictureBox2, pictureBox4, pictureBox6,
};
for(int i=0; i < allWinningMoves.Length; i+=3)
{
if(allWinningMoves[i].Image != null)
{
if (allWinningMoves[i].Image == allWinningMoves[i + 1].Image && allWinningMoves[i].Image == allWinningMoves[i+2].Image)
{
if (allWinningMoves[i].Image == player1.Image)
return Winner.Player1;
else
return Winner.Player2;
}
}

}
//Check for empty cell
PictureBox[] allPictures = {pictureBox0,
pictureBox1,
pictureBox2,
pictureBox3,
pictureBox4,
pictureBox5,
pictureBox6,
pictureBox7,
pictureBox8,
};

//Clear all Game board cells;
foreach (var p in allPictures)
if (p.Image == null)
return Winner.None;

//It's a draw
return Winner.Draw;
}
void ShowTurn()
{
string status = "";
string msg = "";

switch (winner)
{
case Winner.None:
if (turn == PlayerTurn.Player1)
status = "Turn: Player 1";
else
status = "Turn: Player 2";
break;
case Winner.Player1:
msg = status = "Player 1 Wins!";
break;
case Winner.Player2:
msg = status = "Player 2 Wins!";
break;
case Winner.Draw:
status = "You suck, it's a draw";
break;
}
lblStatus.Text = status;
if (msg != "")
MessageBox.Show(msg, "Winner!", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
public Form1()
{
Thread t = new Thread(new ThreadStart(SplashStart));
t.Start();
Thread.Sleep(4800);

InitializeComponent();

t.Abort();
}

public void SplashStart()
{
Application.Run(new Form3());
}

private void label1_Click(object sender, EventArgs e)
{

}

private void label1_Click_1(object sender, EventArgs e)
{

}

private void label3_Click(object sender, EventArgs e)
{

}

private void lblStatus_Click(object sender, EventArgs e)
{

}

private void OnClick(object sender, EventArgs e)
{
PictureBox p = sender as PictureBox;

if (p.Image != null)
return;
if (turn == PlayerTurn.None)
return;


if (turn == PlayerTurn.Player1)
p.Image = player1.Image;
else
p.Image = player2.Image;

//Check for winner
winner = GetWinner();
if (winner == Winner.None)
{

//Change turns
turn = (PlayerTurn.Player1 == turn) ? PlayerTurn.Player2 : PlayerTurn.Player1;
}
else
{
turn = PlayerTurn.None;
}
ShowTurn();
}

private void Form1_Load(object sender, EventArgs e)
{
OnNewGame();
}

private void btnNewGame_Click(object sender, EventArgs e)
{
var result = MessageBox.Show("Are you sure you want to start a new game?",
"New Game",
MessageBoxButtons.YesNo,
MessageBoxIcon.Question);
if(result == DialogResult.Yes)
OnNewGame();
}

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
var result = MessageBox.Show("Are you sure you want to exit now?",
"Exit",
MessageBoxButtons.YesNo,
MessageBoxIcon.Question);
if(result == DialogResult.No)
e.Cancel = true;
}
}
}


Splash Screen Code:

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

namespace WindowsFormsApp1
{
public partial class Form3 : Form
{
public Form3()
{
InitializeComponent();
}

private void pictureBox1_Click(object sender, EventArgs e)
{

}

private void timer1_Tick(object sender, EventArgs e)
{
progressBar1.Increment(1);
if (progressBar1.Value == 100)
timer1.Stop();
}
}
}