Navy robotics engineer Bill Porter designed and built this fantastic Tetris-playing LED tie in a mere four hours to impress a roomful of eighth graders. But the wonderful LED light show that automatically plays Tetris on its own should impress anyone who's ever had to kill time at work, and didn't have access to Solitaire.
Some 80 multi-color LEDs wired to a DigiSpark microcontroller are controlled by a stripped-down self-playing version of Tetris that—for the time being at least—randomly fall and move about the tie. All-in-all the project only cost Bill about $50, but being able to impress a group of thirteen year olds who've probably never actually played Tetris? That's priceless. [Bill Porter via Geeks Are Sexy]