This is a an open source JavaScript implementation of Conway's Game of Life. Source is available here.
The Game of Life, is a 'game' that, in a broad sense, simulates evolution. The game consists of a 'world' filled with the building blocks of life. For the sake of simplicity, let's think of them as cells, where cells are either alive or dead. The game is kickstarted using a pattern of alive cells. This initial pattern constitutes the first generation[0] of life. With each generation, this initial pattern or form of 'life' goes through various mutations, resulting in a multitude of varied patterns of 'life'. The way these patterns generated are governed by a set of rules.
[0] On evolutionary timescales, a generation can range from a thousand to a million years.