The title "zero-player game" kills the fun outright, doesn't it? Well, not this time. This game is one of the oldest in the history of computer games, and it is still very popular throughout the world because of it's endless possibilities and surprisingly simple rules, which are easy to implement even on the lowest-end hardware. Actually, this game is one of the most interesting branches of cellural-automata theory. However, don't get frightened by the sounding of that.

The idea of the game is very simple - there is some pattern of cells, called "live" and "dead", which evolves according to four rules of life to another pattern, and so on for eternity. Of course, most of us can't wait that long, therefore game usually ends when the pattern stabilises, meaning that it doesn't evolve anymore (it is called "still life", and there are quite a few of them discovered), starts to repeat itself (these are called "oscilators" if they don't move and "spaceships" if they are moving).

The only thing the player can do is to make the first pattern. And it's a great fun, actually, when you launch the game and see your creation mutate and evolve into something entirely new and unexpected, even though you don't control the process at all. After pressing the "Play" button, computer starts these simple calculations to create another pattern:

• if the cell is alive and surrounded by one or no other alive cells, it dies because of loneliness;
• if the cell is alive and surrounded by four or more alive cells, it dies because it runs out of breathing space;
• otherwise, the cell remains alive;
• if the cell is dead and has exactly three alive neighbours, it becomes alive (a new cell is born);
• otherwise, the cell remains dead.

All the calculations are carried out simultaniously, and one cycle of calculations is called "tick" or, more conveniently, "generation". As I have already said, albeit these rules are very easy to implement into computer, they give so fun, unexpected and complex results out of initial patterns that you simply can't resist trying some more patterns.

If you want to try it out, you can use one of the Java applets found on the Internet or download an application. Personally, I used a program called (exceptionally originally) "Life!", however, Life32 seems to be a bit better. You can download it from here, it seems to be freeware. And, of course, what is the game without patterns. Throughout game's history many exceptionally interesting patterns were found, and you can download some files from Life pattern catalog (the best part of it is that you can actually check them out with a built in applet and don't need to download anything at all - great, if you just want to have a look at the game), or just redraw some of the patterns from Conway's life glossary (mind it, it is huge and requires a lot of time to load).

The image was taken from free open online encyclopedia Wikipedia. By the way, it features a good article about the game, it's worth to read if I managed to get you interested.