GtkLife is a fast, featureful, open-source Conway's Life program.

Conway's Life is a form of artificial life (specifically, a cellular automaton)-
one of the simplest there is. There are only a few rules:

    The game is played on a rectangular grid, where each cell is either alive or dead.
    Each generation is computed from the state of the previous generation, using rules 3 and 4:
    A live cell with 2 or 3 live neighbors (adjacent cells, including diagonals) lives on. Otherwise it dies.
    A dead cell with exactly 3 live neighbors comes to life. 
                
That's all there is to it. Yet fascinating behavior arises from these simple 
rules.