TicTacToe C# Console

using System;
using System.Collections.Generic;
using System.Text;

namespace TicTacToe
{
    class Program
    {
        public static void Main(string[] args)
        {
            string coords;
            string gameWon;
            Game.Initialise(false); //initialise only. set to true if re-setting
            Console.WriteLine("Welcome to TicTacToe!");
            while (true)
            {
                Game.ChoosePlayer();    //give choice of X or O
                Game.PrintGame();       //print ASCII grid
                while (true)
                {
                    coords = GetCoords(); //get coordinates of grid to play
                    Game.SetGrid(coords); // place X or O in the grid array at chosen coordinate
                    Game.PrintGame();
                    gameWon = Game.CheckGameOver(); //one of 4 return values X, O = winner, Q = all grid places filled with no winner, "" continue
                    if (gameWon == "X" || gameWon == "O")
                    {
                        Console.WriteLine("Player '" + Game.GetPlayer() + "' WINS!");
                        break;
                    }
                    else if (gameWon == "Q")
                    {
                        Console.WriteLine("Game is a DRAW!");
                        break;
                    }
                    //the following lines only run if no winner or draw
                    Game.switchPlayer(); // change from X to O or vice-versa
                    Console.WriteLine(); // space before next grid drawn
                }
                if (PlayAgain())
                {
                    Game.Initialise(true); //reset arrays
                }
                else
                {
                    break;
                }
            }
            //user did not want to continue
            Console.WriteLine("Thank you for playing TicTacToe");
            Console.Write("Press any key to continue . . . ");
            Console.ReadKey(true);
        }
        static string GetCoords()
        {
            // array of acceptable keyboard inputs
            string[] goodResponse = {"a1","a2","a3","b1","b2","b3","c1","c2","c3","1a","1b","1c","2a","2b","2c","3a","3b","3c"};
            string response;
            int xcoord;
            while (true)
            {
                response = Game.Input("Player '" + Game.GetPlayer() + "' - Type your coords (e.g. a1) > ").ToLower();
                // check if response found in array of acceptable responses
                if(Array.Find(goodResponse, s => s.Equals(response)) != string.Empty)
                {
                    // ensure coords are in letter+number format
                    if(int.TryParse( response.Substring(0,1), out xcoord)) //1a, 3c
                    {
                        //reverse coordinates 1a -> a1
                        response = response.Substring(1,1) + response.Substring(0,1);
                    }
                    //check if coords available (not already containing X or O)
                    if( Game.getGrid(response).Equals(' '))
                    {
                        break;
                    }
                }
            }
            return response;
        }
        static bool PlayAgain()
        {
            if(Game.Input("Play Again? (y/n)").ToLower() == "y")
            {
                return true;
            }
            else
            {
                return false;
            }
        }
    }


    static class Game
    {
        //arrays and other module level variables
        private static char Player;
        private static Dictionary<char, byte> asciiDict = new Dictionary<char, byte>();
        private static byte[][] byteArray = new byte[8][];
        private static char[] gameArray;

        // function to convert a byte array of ASCII codes into a string
        // Obscure graphics ╗
        private static string ASCII8ToString(byte[] ASCIIData)
        {
            var e = Encoding.GetEncoding("437");
            return e.GetString(ASCIIData);
        }
        public static string CheckGameOver()
        {
            string gameWon = string.Empty;
            bool gameOver = false;
            string testString;
            /*grid:
             * |O| | |
             * |X|X|X|
             * |O|O| |
             * This layout equates to:
             * gameArray = "O  XXXOO " (9 places)
             */
            for (int i = 0; i < 8; i = i + 3)
            {
                //checks 3 rows for full set of x or O
                testString = CheckWinner(new int[]{i, i + 1, i + 2});
                if (testString == "X" || testString == "O")
                {
                    gameWon = testString;
                    gameOver = true;
                    break;
                }
            }
            if(!gameOver)
            {
                for (int i = 0; i < 3; i++)
                {
                    testString = CheckWinner(new int[]{i, i + 3, i + 6});
                    if (testString == "X" || testString == "O")
                    {
                        gameWon = testString;
                        gameOver = true;
                        break;
                    }
                }
            }
            if(!gameOver)
            {
                testString = CheckWinner(new int[]{0, 4, 8});
                if (testString == "X" || testString == "O")
                {
                    gameWon = testString;
                    gameOver = true;
                }
            }
            if(!gameOver)
            {
                testString = CheckWinner(new int[]{2, 4, 6});
                if (testString == "X" || testString == "O")
                {
                    gameWon = testString;
                    gameOver = true;
                }
            }
            //test for full grid with no winner
            if(!gameOver)
            {
                //no winner yet. Assume game grid is full
                gameOver = true;
                // test for gaps in game grid
                if(!Array.Exists(gameArray, s => s.Equals(' ')))
                {
                    gameWon = "Q";
                }
            }
            return gameWon; // X , O, Q or empty string
        }
        private static string CheckWinner(int[] arrCheck)
        {
            string check = Convert.ToString(gameArray[arrCheck[0]]) + Convert.ToString(gameArray[arrCheck[1]]) + Convert.ToString(gameArray[arrCheck[2]]);
            string gameWon = string.Empty;
            if (check == "XXX")
            {
                gameWon = "X";
            }
            else if (check == "OOO")
            {
                gameWon = "O";
            }
            return gameWon;
        }
        public static void ChoosePlayer()
        {
            string player;
            while (true)
            {
                player = Input("Choose 'X' or 'O' to play");
                if (player == "X" || player == "x")
                {
                    player = "X";
                    break;
                }
                else if (player == "o" || player == "O" || player == "0")
                {
                    player = "O";
                    break;
                }
            }
            char[] arrPlayer = player.ToCharArray();
            Player = arrPlayer[0];
        }
        private static string Decode(byte[] input)
        {
            //convert input byte array to string
            return ASCII8ToString(input);
        }
        public static char getGrid(string coord)
        {
            // get the status of the byte stored in the equivalent of the grid centre of the chosen coordinate
            byte status = 0;
            if      (coord == "a1") {status = byteArray[1][5]; }
            else if (coord == "a2") {status = byteArray[1][9]; }
            else if (coord == "a3") {status = byteArray[1][13];}
            else if (coord == "b1") {status = byteArray[3][5]; }
            else if (coord == "b2") {status = byteArray[3][9]; }
            else if (coord == "b3") {status = byteArray[3][13];}
            else if (coord == "c1") {status = byteArray[5][5]; }
            else if (coord == "c2") {status = byteArray[5][9]; }
            else if (coord == "c3") {status = byteArray[5][13];}
            //Convert to char and return (X, O or space)
            return Convert.ToChar(status);
        }
        public static char GetPlayer()
        {
            return Player;
        }
        public static void Initialise(bool reset)
        {
            if(!reset) //when game is started
            {
                //fill the public 2D (8 x 16) Array of bytes with 0
                for(int i = 0; i < 8; i++)
                {
                    byteArray[i] =  new byte[]{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
                }
                //fill the public dictionary with char keys and byte values (Use single quotes for char!)
                asciiDict.Add('=', 200); // ╚
                asciiDict.Add('-', 205); // ═
                asciiDict.Add('/', 188); // ╝
                asciiDict.Add('|', 186); // ║
                asciiDict.Add('~', 201); // ╔
                asciiDict.Add('%', 187); // ╗
                asciiDict.Add('+', 206); // ╬
                asciiDict.Add('^', 202); // ╩
                asciiDict.Add('`', 203); // ╦
                asciiDict.Add('$', 204); // ╠
                asciiDict.Add('*', 185); // ╣
                asciiDict.Add(' ', 32);
                asciiDict.Add('A', 65);
                asciiDict.Add('B', 66);
                asciiDict.Add('C', 67);
                asciiDict.Add('1', 49);
                asciiDict.Add('2', 50);
                asciiDict.Add('3', 51);
            }
            // reset runs from here
            // create and fill a local 2D (8 x 16) array of chars
            // It is easier to use obscure chars that can be directly typed in and convert them
            char[][] charArray = new char[8][];
            charArray[0] = "   ~---`---`---%".ToCharArray();
            charArray[1] = " A |   |   |   |".ToCharArray(); //X or O will occupy charArray[1][5], [1][9] and [1][13]
            charArray[2] = "   $---+---+---*".ToCharArray();
            charArray[3] = " B |   |   |   |".ToCharArray(); //X or O will occupy charArray[3][5], [3][9] and [3][13]
            charArray[4] = "   $---+---+---*".ToCharArray();
            charArray[5] = " C |   |   |   |".ToCharArray(); //X or O will occupy charArray[5][5], [5][9] and [5][13]
            charArray[6] = "   =---^---^---/".ToCharArray();
            charArray[7] = "     1   2   3  ".ToCharArray();

            /*change all the values in byteArray with bytes based on the ASCII code of the characters
             * that should be eventually printed to the console to draw the game grid.
             * substitute the keyboard characters used in the charArray above with the ASCII codes for the old DOS based
             * graphics. Use the Dictionary to look up the byte values from the character key
             * Normal characters (ABC123XO) have their ASCII codes inserted into the array when appropriate
             */
            byte b;
            char c;
            for (int j = 0; j < 8; j++)
            {
                for (int i = 0; i < charArray[j].Length; i++)
                {
                    c = charArray[j][i];
                    b = asciiDict[c];
                    byteArray[j][i] = b;
                }
            }
            gameArray = "         ".ToCharArray(); //initialise or reset to 9 space characters
        }
        // mimics Python's input() function
        public static string Input(string prompt)
        {
            Console.Write(prompt + "_");
            return(Console.ReadLine());
        }
        public static void PrintGame()
        {
            for (int i = 0; i < 8; i++)
            {
                Console.WriteLine(Decode(byteArray[i]));
            }
        }
        public static void SetGrid(string coord)
        {
            // status = X, O
            if (coord == "a1")
            {
                byteArray[1][5] = Convert.ToByte(Player);
                gameArray[0] =  Player;
            }
            else if (coord == "a2")
            {
                byteArray[1][9] = Convert.ToByte(Player);
                gameArray[1] =  Player;
            }
            else if (coord == "a3")
            {
                byteArray[1][13] = Convert.ToByte(Player);
                gameArray[2] =  Player;
            }
            else if (coord == "b1")
            {
                byteArray[3][5] = Convert.ToByte(Player);
                gameArray[3] =  Player;
            }
            else if (coord == "b2")
            {
                byteArray[3][9] = Convert.ToByte(Player);
                gameArray[4] =  Player;
            }
            else if (coord == "b3")
            {
                byteArray[3][13] = Convert.ToByte(Player);
                gameArray[5] =  Player;
            }
            else if (coord == "c1")
            {
                byteArray[5][5] = Convert.ToByte(Player);
                gameArray[6] =  Player;
            }
            else if (coord == "c2")
            {
                byteArray[5][9] = Convert.ToByte(Player);
                gameArray[7] =  Player;
            }
            else if (coord == "c3")
            {
                byteArray[5][13] = Convert.ToByte(Player);
                gameArray[8] =  Player;
            }
        }
        public static void switchPlayer()
        {
            if (Player == 'X')
            {
                Player = 'O';
            }
            else
            {
                Player = 'X';
            }
        }
    }
}