The Game of Life in C#. Nothing special. Wanted to try rendering something using GDI+ in winforms as simply as possible while still being fast. Abusing a Timer in this way is kind of nasty, but that coupled with unsafe bitmap drawing is actually pretty performant for simple things.

Life.cs

using System;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Windows.Forms;

namespace chip8
{

	public partial class MainForm : Form
	{
		Graphics g;
		Stopwatch watch = new Stopwatch();
		long logicTime = 0;
		long drawTime = 0;
		
		const int cellsWidth = 400;
		const int cellsHeight = 300;
		
		int[] cells = new int[cellsWidth * cellsHeight];
		
		static Random rand = new Random();
		Bitmap raster = new Bitmap(cellsWidth, cellsHeight, PixelFormat.Format24bppRgb);
		
		public MainForm()
		{
			InitializeComponent();
			this.ClientSize = new Size(cellsWidth*2,cellsHeight*2);
			drawTimer.Interval = 1;
			drawTimer.Tick += (TimerTick);
			drawTimer.Start();
			g = this.CreateGraphics();
			g.SmoothingMode = SmoothingMode.None;
			g.InterpolationMode = InterpolationMode.NearestNeighbor;
			g.PixelOffsetMode = PixelOffsetMode.Half;
			g.Clear(Color.White);

			Seed();
		}
		
		void Seed()
		{
			for (int i = 0; i < cells.Length; i++)
				cells[i] = rand.Next(0, 2);
		}
		
		void UpdateCells()
		{
			var newCells = (int[])cells.Clone();
			for (int i = 0; i < cells.Length; i++) {
				int liveNeighbors = 0;
				liveNeighbors += cells.WrappedLookup(i - 1); //left
				liveNeighbors += cells.WrappedLookup(i + 1); //right
				liveNeighbors += cells.WrappedLookup(i + cellsWidth);//bottom
				liveNeighbors += cells.WrappedLookup(i - cellsWidth);//top
				
				liveNeighbors += cells.WrappedLookup(i - 1 - cellsWidth);//top-left
				liveNeighbors += cells.WrappedLookup(i + 1 - cellsWidth);//top-right
				liveNeighbors += cells.WrappedLookup(i - 1 + cellsWidth);//bottom-left
				liveNeighbors += cells.WrappedLookup(i + 1 + cellsWidth);//bottom-right
			
				if (cells[i] == 0 && liveNeighbors == 3) {
					newCells[i] = 1;
					continue;
				}
				
				if (liveNeighbors < 2)
					newCells[i] = 0;
				else if (liveNeighbors == 2 || liveNeighbors == 3)
					continue;
				else if (liveNeighbors > 3)
					newCells[i] = 0;
			}
			
			cells = newCells;
		}
		
		int x = 0;
		int y = 0;
		
		void SafeDraw()
		{
			for (int i = 0; i < cells.Length; i++) {
				if (cells[i] == 0) {
					raster.SetPixel(x++, y, Color.White);
				} else if (cells[i] == 1) {
					raster.SetPixel(x++, y, Color.Black);
				}
				
				if (x == cellsWidth) {
					y++;
					x = 0;
				}
				if (y == cellsHeight)
					x = y = 0;
			}
			
			g.DrawImage(raster, 0, 0, this.ClientRectangle.Width, this.ClientRectangle.Height);			
		}
				
		unsafe void FastDraw()
		{
			BitmapData bitmapData = raster.LockBits(new Rectangle(0, 0, raster.Width, raster.Height), ImageLockMode.ReadWrite, raster.PixelFormat);

			var ptrFirstPixel = (byte*)bitmapData.Scan0;
         	
			int ptrSeek = 0;
			for (int i = 0; i < cells.Length; i++) {
				if (cells[i] == 1) {
					ptrFirstPixel[ptrSeek++] = (byte)0;
					ptrFirstPixel[ptrSeek++] = (byte)0;
					ptrFirstPixel[ptrSeek++] = (byte)0;
				} else {
					ptrFirstPixel[ptrSeek++] = (byte)255;
					ptrFirstPixel[ptrSeek++] = (byte)255;
					ptrFirstPixel[ptrSeek++] = (byte)255;
				}
			}
			raster.UnlockBits(bitmapData);
			g.DrawImage(raster, 0, 0, this.ClientRectangle.Width, this.ClientRectangle.Height);	
		}
		
		bool fastDrawing = true;
		
		void TimerTick(object sender, EventArgs e)
		{
			
			watch.Start();
			UpdateCells();
			logicTime = watch.ElapsedMilliseconds;
			watch.Restart();
			if (fastDrawing)
				FastDraw();
			else
				SafeDraw();
			drawTime = watch.ElapsedMilliseconds;
			
			if (fastDrawing)
				Text = "Life - " + logicTime.ToString() + "ms logic, " + drawTime + "ms draw" + " (unsafe)";
			else
				Text = "Life - " + logicTime.ToString() + "ms logic, " + drawTime + "ms draw" + " (safe)";
			watch.Reset();
		}

		void Clicked(object sender, MouseEventArgs e)
		{
			if (e.Button == MouseButtons.Left)
				Seed();
			else if (e.Button == MouseButtons.Right)
				fastDrawing = !fastDrawing;
	
		}
	}
		
	public static class Util
	{
		public static int WrappedLookup(this int[] array, int index)
		{			
			if (index < 0) {
				return array[(array.Length - 1) + (index % (array.Length - 1))];
			} else
				return array[index % (array.Length - 1)];
		}
	}
}