Updated: Feb 1, 2019
ActivePuzzle robots work with no central processing unit, in a system called Braitenberg Vehicle or BEAM robotics: sensors send their input to neighbor pieces, and this signal spreads along the robot.
When the signal reaches actuators (e.g. motor, light, buzzer) it activates it with the signal value (analog). This mechanism is also called Sense-Act. You customize the robot by building combinations of Sense-Acts and their relative direction.