Install Common LISP. On OS X using homebrew:
$ brew install clisp
Change to the folder and start the game by calling
$ clisp -i game-of-life.lisp
You can now use the following commands:
> (print-world) ; show the current status of the world
> (spawn-random-cell) ; spawn a random cell anywhere
> (spawn-cell-at 2 4) ; spawns a living cell at x: 2, y: 4
> (next-generation) ; proceed one generation (calls `print-world`)
Typical usage involves spawning some cells manually at desired locations and call next-generation a few times.