Complete program that plays MineSweeper in the terminal in 100 non-whitespace lines of code. Ported from https://radanskoric.com/experiments/minesweeper-100-lines-of-clean-ruby

Program.cs

if (args.Length == 3)
{
    Play(args.Select(int.Parse).ToArray());
}
else
{
    Console.WriteLine("Usage: Minesweeper width height mineCount (e.g. Minesweeper 12 6 6)");
}

static void Play(params int[] args)
{
    var game = new Game(Board.GenerateRandom(args[0], args[1], args[2]));
    var renderer = new AsciiRenderer(game);
    renderer.Render();
    while (true)
    {
        Console.Write("Type click coordinate as 'x, y' (0 based)> ");
        if (Console.ReadLine().Split(",") is [var x, var y])
        {
            var result = game.Reveal(new Coordinate(int.Parse(x), int.Parse(y)));
            renderer.Render();
            if (result is Game.State.Win or Game.State.Lose)
            {
                Console.WriteLine($"You {result}!");
                return;
            }
        }
    }
}

record Coordinate(int X, int Y)
{
    static readonly Coordinate[] neighbors = (
        from x in new[] { -1, 0, 1 }
        from y in new[] { -1, 0, 1 }
        select new Coordinate(x, y)
    ).Except([new(0, 0)]).ToArray(); 

    public bool IsNeighbor(Coordinate other) =>
        new[] { Math.Abs(X - other.X), Math.Abs(Y - other.Y) }.Max() <= 1;

    public IEnumerable<Coordinate> Neighbors(int boardWidth, int boardHeight) =>
        neighbors
            .Select(neighbor => this + neighbor)
            .Where(neighbor => !(neighbor.X < 0 || neighbor.X >= boardWidth || neighbor.Y < 0 || neighbor.Y >= boardHeight));

    public static Coordinate operator +(Coordinate a, Coordinate b) => new(a.X + b.X, a.Y + b.Y);
}

record Board(int Width, int Height, Coordinate[] Mines)
{
    public record Mine() : BoardCell;
    public record Empty(int NeighborMines) : BoardCell;
    public record BoardCell();

    public static Board GenerateRandom(int width, int height, int mineCount)
    {
        var fullBoard = from x in Enumerable.Range(0, width)
                        from y in Enumerable.Range(0, height)
                        select new Coordinate(x, y);
        return new Board(width, height, Random.Shared.GetItems(fullBoard.ToArray(), mineCount));
    }

    public BoardCell Cell(Coordinate coordinate) =>
        Mines.Contains(coordinate) ? new Mine() : new Empty(CountNeighbors(coordinate));

    int CountNeighbors(Coordinate coordinate) => Mines.Count(mine => mine.IsNeighbor(coordinate));
}

class Game(Board board)
{
    public enum State { Play, Win, Lose }
    public Board Board => board;
    readonly Board.BoardCell[] cells = new Board.BoardCell[board.Height * board.Width];
    readonly Board.Empty CellWithNoAdjacentMines = new(0);

    public State Reveal(Coordinate coordinate)
    {
        var index = CellIndex(coordinate);
        if (cells[index] is not null) return State.Play;

        cells[index] = board.Cell(coordinate);

        if (cells[index] is Board.Mine) return State.Lose;
        if (cells[index] == CellWithNoAdjacentMines) RevealNeighbors(coordinate);

        return cells.Count(c => c is null) == board.Mines.Length ? State.Win : State.Play;
    }

    public Board.BoardCell Cell(Coordinate coordinate) => cells[CellIndex(coordinate)];

    public int CellIndex(Coordinate coordinate) => coordinate.Y * board.Width + coordinate.X;

    public void RevealNeighbors(Coordinate coordinate) =>
        coordinate.Neighbors(board.Width, board.Height).ToList().ForEach(n => Reveal(n));
}

class AsciiRenderer(Game grid)
{
    public void Render(TextWriter? stdout = null)
    {
        stdout ??= Console.Out;
        foreach (var y in Enumerable.Range(0, grid.Board.Height))
        {
            foreach (var x in Enumerable.Range(0, grid.Board.Width))
            {
                stdout.Write(grid.Cell(new Coordinate(x, y)) switch
                {
                    null => "#",
                    Board.Mine => "*",
                    Board.Empty { NeighborMines: 0 } => "_",
                    Board.Empty { NeighborMines: int mineCount } => mineCount.ToString(),
                });
            }
            stdout.WriteLine();
        }
    }
}