The rules of the ‘123’ Game are described in the ‘123 Game – all MCU-free’ article. Naturally, a more luxurious version can be built with a microcontroller. Here you don’t have to manipulate a probe tip to play the game, and the playing field is formed by LEDs instead of mini-sockets. A microcontroller drives the LED array, and three input buttons take over the role of the probe tip. In contrast to the simple version, the built-in ‘intelligence’ of the microcontroller also allows two humans to play against each other.