Here's a video for a Conway's Game of Life (wiki) kit from Make.
In 1970, John Conway came up with a 1-player game called Game of Life. The Game of Life is a mathematical game that simulates 'colonies' that grow or die based on how crowded or lonely they are and is known for the way it creates a beautiful organic display out of randomness.
Here is a fun electronic kit that plays Conway's Game of Life. Make one kit and keep it on your desk, or attach multiple kit modules together to create a large display, like a cube.