Fortress Yin Yang
(Published on 20. June 2026, 01:00 by yttrio)
Rules:
Normal Sudoku rules apply.
Yin Yang: Shade some cells such that all shaded cells are orthogonally connected, all unshaded cells are orthogonally connected, and no 2x2 area is fully shaded or fully unshaded.
Shaded cells act as fortress (maximum) cells: shaded cells must be larger than all orthogonal neighbors of the cell that are unshaded.
A digit in a cell with an arrow counts the total number of shaded cells seen in the direction of the arrow (not counting the cell itself).
6x6 Example:
The image below shows a sample 6x6 puzzle and solution with the same rule set.
Play the example 6x6 in SudokuPad.
Solution code: Digits in shaded cells in row 4 (left to right) followed by digits in shaded cells in column 4 (top to bottom)
Comments
yesterday, 19:32 by madhupt
What a cool puzzle! So smooth and enjoyable. It is easy to make a mistake and that is what I did and had to rewind all the way back but finally did it. Very nice deductions all the way. Thanks for sharing this!
on 22. June 2026, 19:59 by DaniK
Wonderful puzzle!
on 22. June 2026, 08:20 by Piatato
Lovely!
on 21. June 2026, 23:47 by Exigus
Fantastic yin yang, very cool construction with so few clues. Thanks!
on 21. June 2026, 18:59 by Fool on Hill
Excellent puzzle - enjoyed it greatly: not the hardest 4/5 rated puzzle, but does require thought..
It is tricky (I know because I have tried in the past) to get Yin Yang working cleanly with the fortress rule. But I hope I will see more people giving it a go, because there are some interesting interactions to be found.
on 21. June 2026, 16:54 by Snookerfan
Brilliant puzzle with fresh logic. Thanks!
on 20. June 2026, 15:36 by Ambrose
Extremely satisfying!
on 20. June 2026, 14:14 by firespire
I did the 6x6. Thanks for the puzzle.
on 20. June 2026, 14:09 by wuc
Brilliant 60 minutes. Awesome puzzle thx.
on 20. June 2026, 13:48 by Franjo
Thank you very much for creating and sharing another wonderful YY-puzzle. So the fantastic journey goes on …
on 20. June 2026, 13:17 by Qodec
Incredible! Another entry in my favorites list!
on 20. June 2026, 13:15 by Chaka
Superb setting! Loved it!
on 20. June 2026, 04:47 by Calvinball
Freaking epic!
on 20. June 2026, 02:55 by yttrio
Corrected solution code
on 20. June 2026, 02:40 by prismic911
I found the solution but the solution code does not work
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My apologies, I had a typo when I originally created the puzzle. The code should be correct now.
~yttrio
