When it came out in 1972, Pong was a marvel of video game design. It's visually simple by today's standards, but it thrilled the first generation of video game players.
You can play it on a computer now. But thanks to Daniel Perdomo and his colleagues, it's also possible to play a physical version in a table-shaped arcade cabinet.
This video shows how it's put together. Magnets move the paddles and ball back and forth between two sheets of glass. The paddles don't actually hit the ball, but the ball ricochets according to the angles of impact to the paddles. It's an incredible technical achievement.