Geometry and arithmetic galore.
Huge thanks to DiMono for test-solving this, which eventually led to a crucial improvement to the beauty of the puzzle.
You can play this puzzle online using f-puzzles: https://f-puzzles.com/?id=y5593j5q.
Good luck cracking this one.
Solution code: The 9 digits in column 2 from top to bottom, followed by the 9 digits in row 2 from left to right, no spaces, for example: 123456789123456789
on 7. April 2023, 10:28 by Yann
I absolutely LOVE this puzzle, the logic is sublime and the grid is beautiful.
Thank you for this masterpiece, Qodec
on 11. January 2023, 05:34 by Samish
I relived the joy I had the first time I solved it when it was featured. It was possibly my favourite puzzle, and still is among them
on 9. September 2022, 14:38 by Niverio
Simply lovely :) Not as hard in today's standards either!
on 24. August 2022, 19:19 by Playmaker6174
Super beautiful, super wonderful design, and what a way to conclude your tour de force there! Really glad that I've enjoyed all of your puzzles and each of them brought lots of joy to me ;)
on 23. August 2022, 17:19 by Agent
Fantastic puzzle! I loved the concept, the execution, the symmetry, and the fact that it was very resilient all the way through. This feels like a very well crafted puzzle.
on 17. September 2021, 06:34 by Vebby
Absolutely stunning! One of the hardest puzzles I've done, which makes it all the more satisfying to solve. Genius construction, take a bow Qodec!