(This description is adapted from Daniel C. Dennett: Darwin's Dangerous Idea. The game of Life was invented by the mathematician John Horton Conway, and first popularized by Martin Gardner in his "Mathematical Games" columns in the Scientific American of October 1970 and February 1971.)

Life is played on a two-dimensional grid, such as a checkerboard, using simple counters, such as pebbles or pennies--or one could go high-tech and play it on a computer screen. It is not a game one plays to win; if it is a game at all, it is solitaire. The grid divides space into square cells, and each cell is either ON or OFF at each moment. Notice that each cell has eight neighbours:

+---+---+---+---+---+ | | | | | | +---+---+---+---+---+ | | NW| N | NE| | +---+---+---+---+---+ | | W | * | E | | +---+---+---+---+---+ | | SW| S | SE| | +---+---+---+---+---+ | | | | | | +---+---+---+---+---+

Time in the life world is discrete, not continuous; it advances in ticks, and the state of the world changes between each two ticks according to the following rule.

Life Physics: For each cell in the grid, count how many of its eight neighbors are ON at the present instant. If the answer is exactly two, the cell stays in its present state (ON or OFF) in the next instant. If the answer is exactly three, the cell in ON in the next instant. Under all other conditions, the cell is OFF.

See the source for the user interface and for the game implementation.

Starting with an InfoSeek search, I found the following web pages of use:

- CMU (overview of traditional applications)
- DEC Research (form with check boxes)
- Catseye (form with textarea)
- Fusebox (Netscape server push)
- Saint Joe (Netscape client pull)