Every board is a working QR code. Tap a light area and it fills in dark. That corrupts the data, but the code keeps scanning right up to the Reed-Solomon error correction limit. Your score is how many moves you make before it breaks.
A solver finds the exact maximum for each puzzle, so a perfect game is a real target. Four difficulty levels change only what you see. A bigger code on Sundays. Free, no account, no cookies, no analytics scripts. Scan any board mid-game and it opens that puzzle.
