A real-life implementation of the evergreen arcade game Tetris was obtained by optically trapping 42 glass microspheres (1 ?m diameter) in a 25 ?m x 20 ?m sized field under a microscope. Their positions are then steered with a computer.
The generation of multiple traps, as well as the computer-steering, is accomplished by the use of acousto-optic deflectors: devices that tune the deflection of a laser beam that have very fast response.

This page contains real-time videos and images of a ?- Tetris game, played live from the computer keyboard. (The appearance of the microspheres is influenced by the use of a contrast-enhancing microscopy technique called differential interference contrast or DIC.)