Summetry
(Published on 15. July 2026, 15:34 by Kaktuslav)
Rules: Normal sudoku rules apply.
Centrally symmetric Yin-Yang: Shade some cells in the grid so that all shaded cells are orthogonally connected, all unshaded cells are orthogonally connected, and no 2×2 region is entirely shaded or entirely unshaded. The shading must also be centrally symmetric: cells mapped to each other by a 180∘ rotation about the center of the grid have the same shading.
Cages: Digits may not repeat within a cage. Each cage contains at least one shaded and one unshaded cell, and the sum of its unshaded digits equals the product of its shaded digits (a sum or product consisting of a single digit is simply that digit).
Solution code: Unshaded digits in row 5 followed by shaded digits in row 7
Comments
on 16. August 2026, 01:14 by koXx
Brilliant interactions of the different rules! An absolute banger of a puzzle!
on 15. August 2026, 23:57 by WildEnte
Made it before midnight. On Day 6 :-)
on 22. July 2026, 14:59 by PatternSpren
What a puzzle! Took me ages to solve but very nice.
on 21. July 2026, 01:47 by pmays123
Elegant. Thank you
on 18. July 2026, 18:07 by Exigus
Amazing yin-yang, some really nice deductions to be had. Thanks!
on 17. July 2026, 17:40 by Djirt
Спасибо, настоящая жемчужина!)
on 17. July 2026, 16:15 by kasperd
This one was only three stars of difficulty for me. I really liked how these rules interacted.
on 17. July 2026, 15:44 by louis0
Found this one very hard but very enjoyable, probably 5* by my standards. Instincts were correct with starting off shading but found it very hard to prove, missing the key deduction for some time. Then slow but steady sudoku after that.
on 17. July 2026, 12:39 by SennyK
What a wonderful construction! :-)
on 16. July 2026, 17:00 by Qodec
Incredibly engaging, top class break-in, and so beautiful! What more could anyone possibly want?
on 16. July 2026, 16:02 by vukkarak
Really nice, both the shading and the sudoku part!
on 16. July 2026, 14:59 by Major314
Favorite puzzle in quite a while, the logic needed for the break in is astonishing !
on 16. July 2026, 13:08 by Franjo
Thank you very much for creating and sharing another brilliant puzzle. Made my day!
on 16. July 2026, 10:39 by amirs
Lovely challenging puzzle. It took me some time to realize how powerful the effects of the symmetry are.
on 15. July 2026, 20:39 by Myxo
Lovely!
on 15. July 2026, 20:01 by Snookerfan
Very tough nut to crack, probably missed something profound beyond the logic I discovered. Thanks for the challenge
