This is super-nerdy, super-cool. Pongmechanik is Pong "reimagined" with the paddles and ball moved around by strings on pulleys and controlled not by a modern computer (transistors, microprocessors) but by a series of telephone relays manufactured in 1958! It even has sound effects, one wooden block is tapped when the ball "hits" the wall and another is tapped when it hits a paddle.
Watch the video, it's really well done. I found the low-bandwidth version to be "good enough" but if the site is currently Slashdotted, check the comments from the Slashdot's story about it for mirrored sites.