I've posted tangentially about pong before. Now /. (slashDot) has an article (artikal?) about some germans who have made an electromechanical version of the venerable game.
No transistors, no cathode ray tubes; just relays, motors, strings, rails, and good clean fun. The "blip" and "blorp" sounds we know and love are made by wood blocks that have been struck by solenoids. This is a masterwork of mechanical beauty. State of the art - 1930.