Mario Ball is my favorite piece in the show. The enormous maze for 2 players is the physical controller for the original Mario Brothers game. Keita built the maze, Vikram wrote the code and basically rebuilt Mario Brothers, and I designed and built the technology behind it.
The controller uses 90 magnetic reed switches which are triggered when a magnetic ball (dressed up as Mario) is rolled around. The Arduino and 6 multiplexers are used in addition to the magnetic reed switches. The maze senses where the ball is and Mario appears at the corresponding location on the original Mario Brothers screen interface.
I love that the controller is built for 2 people and is large and heavy enough so that it is almost impossible for one person to play alone. It even has cute ceramic and brass handles to indicate where the players should hold it.