Tetris (with theme song) in the C# console.

ConsoleTetris.cs

// Erin Eccleston 2018
// Still buggy, btw...

using System;
using System.Timers;
using static System.Console;
using System.Collections.Generic;

static class Tetris
{
    enum CellStates { Empty, Dead, Alive }
    enum Movement { Left, Down, Right, RotLeft, RotRight }

    static float SpeedUp = 0.8f;
    static float Delay = 1000;
    const int Height = 22;
    const int Width = 10;

    static CellStates[,] World = new CellStates[Width, Height];
    static Random Rand = new Random();
    static Timer Timer = new Timer();

    static int[,] Pieces = new int[,] { { 0, 1, 1, 1, 2, 1, 3, 1 }, { 0, 0, 0, 1, 1, 1, 2, 1 }, { 0, 1, 1, 1, 2, 0, 2, 1 },
        { 1, 0, 2, 0, 1, 1, 2, 1 }, { 0, 1, 1, 0, 1, 1, 2, 0 }, { 0, 1, 1, 0, 1, 1, 2, 1 }, { 0, 0, 1, 0, 1, 1, 2, 1 } };

    static void Main()
    {
        CursorVisible = false;
        Title = "TETRIS";
        SetWindowSize(Width * 2, Height + 1);

        System.Threading.Tasks.Task.Run((Action)PlaySong);

        SpawnPiece();

        Draw();

        Timer.Elapsed += Tick;
        Timer.Interval = Delay;
        Timer.Start();

        ConsoleKeyInfo cki;
        while ((cki = ReadKey(true)) != null)
            Input(cki.Key);
    }

    static void Input(ConsoleKey key)
    {
        switch (key)
        {
            case ConsoleKey.Q:
                break;
            case ConsoleKey.E:
                break;
            case ConsoleKey.A:
                MovePiece(Movement.Left);
                break;
            case ConsoleKey.S:
                Tick(null, null);
                break;
            case ConsoleKey.D:
                MovePiece(Movement.Right);
                break;
            case ConsoleKey.Escape:
                Environment.Exit(Environment.ExitCode);
                break;
        }
    }

    static void SpawnPiece()
    {
        int rand = Rand.Next(7);
        bool exit = false;

        for (int i = 0; i < 8; i += 2)
        {
            if (World[Pieces[rand, i] + Width / 2 - 2, Pieces[rand, i + 1]] != CellStates.Empty)
                exit = true;
            else
                World[Pieces[rand, i] + Width / 2 - 2, Pieces[rand, i + 1]] = CellStates.Alive;
        }

        Draw();

        if (exit) Environment.Exit(Environment.ExitCode);
    }

    static void Draw()
    {
        System.Text.StringBuilder sb = new System.Text.StringBuilder();

        for (int y = 0; y < Height; y++)
        {
            for (int x = 0; x < Width; x++)
                sb.Append(World[x, y] == CellStates.Empty ? "░░" : "██");
            sb.AppendLine();
        }

        Clear();
        Write(sb.ToString());
    }

    static void KillAll()
    {
        for (int y = 0; y < Height; y++)
            for (int x = 0; x < Width; x++)
                if (World[x, y] == CellStates.Alive)
                    World[x, y] = CellStates.Dead;

        RemoveLines();
        SpawnPiece();
    }

    static void RemoveLines()
    {
        for (int y = 0; y < Height; y++)
        {
            int filled = 0;
            for (int x = 0; x < Width; x++)
                if (World[x, y] != CellStates.Empty)
                    filled++;

            if (filled == Width)
            {
                Delay *= SpeedUp;

                for (int i = y - 1; i >= 0; i--)
                {
                    for (int x = 0; x < Width; x++)
                    {
                        if (World[x, i] != CellStates.Empty)
                            World[x, i + 1] = CellStates.Dead;
                        World[x, i] = CellStates.Empty;
                    }
                }
            }

        }
    }

    static void Tick(object sender, ElapsedEventArgs e)
    {
        MovePiece(Movement.Down);

        Timer.Interval = Delay;
        Timer.Start();
    }

    static void MovePiece(Movement direction)
    {
        HashSet<Point> toUpdate = new HashSet<Point>();

        for (int x = 0; x < Width; x++)
        {
            for (int y = 0; y < Height; y++)
            {
                if (World[x, y] == CellStates.Alive)
                {
                    if (y == Height - 1 || World[x, y + 1] == CellStates.Dead)
                    {
                        KillAll();
                        toUpdate = new HashSet<Point>();
                        break;
                    }
                    else
                    {
                        toUpdate.Add(new Point(x, y));
                    }
                }
            }
        }

        int xOff = 0;
        int yOff = 0;

        switch (direction)
        {
            case Movement.Left:
                xOff = -1;
                break;
            case Movement.Down:
                yOff = 1;
                break;
            case Movement.Right:
                xOff = 1;
                break;

        }

        bool valid = true;
        foreach (Point point in toUpdate)
        {
            valid = point.x + xOff >= 0 && point.x + xOff < Width && point.y + yOff >= 0 && point.y + yOff < Height;
            if (!valid) break;
        }

        if (valid)
        {
            foreach (Point point in toUpdate)
                World[point.x, point.y] = CellStates.Empty;
            foreach (Point point in toUpdate)
                World[point.x + xOff, point.y + yOff] = CellStates.Alive;

            Draw();
        }
    }

    //https://gist.github.com/XeeX/6220067
    static void PlaySong()
    {
        Beep(1320,500);Beep(990,250);Beep(1056,250);Beep(1188,250);Beep(1320,125);Beep(1188,125);Beep(1056,250);Beep(990,250);Beep(880,500);Beep(880,250);Beep(1056,250);Beep(1320,500);Beep(1188,250);Beep(1056,250);Beep(990,750);Beep(1056,250);Beep(1188,500);Beep(1320,500);Beep(1056,500);Beep(880,500);Beep(880,500);System.Threading.Thread.Sleep(250);Beep(1188,500);Beep(1408,250);Beep(1760,500);Beep(1584,250);Beep(1408,250);Beep(1320,750);Beep(1056,250);Beep(1320,500);Beep(1188,250);Beep(1056,250);Beep(990,500);Beep(990,250);Beep(1056,250);Beep(1188,500);Beep(1320,500);Beep(1056,500);Beep(880,500);Beep(880,500);System.Threading.Thread.Sleep(500);PlaySong();
    }

    struct Point
    {
        public int x, y;

        public Point(int x, int y)
        {
            this.x = x;
            this.y = y;
        }
    }
}