Tetris (form1.cs)

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 Tetris
{
    public partial class frm_Main : Form
    {
        const int spalten = 11;
        const int zeilen = 22;
        PictureBox[,] matrix = new PictureBox[spalten, zeilen];
        int field_size = 20;
        int stone_x = spalten/2;
        int m_stone_y = 0;
        int m_zeitspanne; //Wert für den Timertick, welcher angibt in welchen Sprüngen der Block nach unten fällt. (Je niedriger desto schneller)

        public frm_Main()
        {
            InitializeComponent();
        }

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

        public void fall()
        {
            m_zeitspanne = 100;
            Timer t1 = new Timer();
            t1.Interval = m_zeitspanne;
            t1.Tick += new EventHandler(t1_Tick);
            t1.Start();
        }

        void t1_Tick(object sender, EventArgs e)
        {
            if (++m_stone_y < zeilen) //"++ston_y" - Wird vor der Abfrage um einen hochgezählt
            {
                if (matrix[stone_x, m_stone_y].Image == null)
                {
                    matrix[stone_x, (m_stone_y - 1 >= 0) ? m_stone_y - 1 : 0].Image = null;
                    matrix[stone_x, m_stone_y].Image = new Bitmap("stein.jpg");
                    matrix[stone_x, m_stone_y].SizeMode = PictureBoxSizeMode.StretchImage;
                }
                else
                    m_stone_y = 0;
            }
            else
                m_stone_y = 0;
        }

        public void SpielfeldErstellen()
        {
            for (int y = 0;y < zeilen;y++)
            {
                for (int x = 0; x < spalten; x++)
                {
                    matrix[x,y] = new PictureBox();
                    matrix[x,y].Size = new System.Drawing.Size (field_size,field_size);
                    matrix[x,y].Location = new System.Drawing.Point (x*field_size+1,y*field_size+1);
                    this.Controls.Add (matrix [x,y]);
                    matrix[x,y].Show();
                }
            }
        }

        void MainFormKeyDown(object sender, KeyEventArgs e)
        {
            int tmpstone_x = stone_x;
            int tmpstone_y = m_stone_y;

            if (e.KeyData == Keys.Left)
            {
                matrix[tmpstone_x, tmpstone_y].Image = null;
                if ((tmpstone_x - 1) > 0)
                {
                    tmpstone_x--;
                    stone_x = tmpstone_x;
                }
                else
                {
                    tmpstone_x = 0;
                }
            }

            if (e.KeyData == Keys.Right)
            {
                matrix[tmpstone_x, tmpstone_y].Image = null;
                if ((tmpstone_x + 1) < 9)
                {
                    tmpstone_x++;
                    stone_x = tmpstone_x;
                }
                else
                {
                    tmpstone_x = 0;
                }
            }
            if (e.KeyData == Keys.Escape) //Form wird geschlossenn, wenn man Escape drückt
            {
                Application.Exit();
            }

            stone_x = tmpstone_x;
            m_stone_y = tmpstone_y;
        }
    }
}