Conway's Game of Life: create a universe and watch it grow!
Click on a cell to toggle it from dead to alive, or select a pattern and place it in the grid. (Try holding Shift and moving your mouse over the grid.) Then click run...
For more details, see https://en.wikipedia.org/wiki/Conway's_Game_of_Life
Developer's note: This was a project to learn to work with HTML Canvas! All graphics are drawn using a single <canvas> element.