Yesterday I was at the NHC CTF, and was not planning to compete. Halfway, I looked at a few challenges, anyway. One was a jigsaw puzzle of a QR code. And through understanding QR codes and logic the options could be reduced from ~1k to an bruteforcible 4. Today, I've been deep into QR code creation, and thinking about what other QR code puzzles are possible. Combine QR with Sudoku and I found QR nanograms. Nanograms are ideal as most are pure logic. So my challenge was to understand which information can be remove to still allow the puzzle to be solved with the Wiki on QR codes. (dark module, timing patterns, and symmetry) I don't yet have a puzzle for you, but it is definitely possible.