Anyone knows what the sudoku puzzle is, and it seems that this robot knows it as well. As a matter of fact, it can solve it all by itself! This autonomous bot is a creation by tilted twister, and used LEGO Mindstorms to make it. It has a light sensor which is used to scan the puzzle matrix. The numbers are recognized by scanning line-by-line, each time advancing just a little bit. After calculating the solution to the puzzle, it writes the digits. Excellent implementation! Find more info here.