Why-Why?
(Eingestellt am 22. November 2025, 17:15 Uhr von SennyK)
I am very proud to present what I believe to be a very hard Yin-Yang sudoku :-)
I hope you will enjoy and I would be really grateful for all the comments and ratings.
Normal sudoku rules apply.
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.
Values: A value of a shaded cell equals its digit increased by the number of (up to 8) surrounding unshaded cells; a value of an unshaded cell equals its digit.
Killer: VALUES in a cage sum to the total given.
Little killer: A clue outside the grid gives the sum of the DIGITS along the indicated diagonal.
Dynamic Fog of War: The grid is partially covered in fog. Entering correct digits may clear fog somewhere in the grid. Guessing won't help.
If you liked this puzzle, I recommend trying out my other puzzles: The Erica Series:★☆☆☆☆: 1, 2, 4, 5, 6, 12, 15, 17, 23, 26, 27
★★☆☆☆: 3, 7, 8, 10, 11, 13, 14, 16, 18, 20, 24, 25
★★★☆☆: 9, 19, 21, 22 Shading/Ying-Yang:
★★☆☆☆: Pretty Odd Shaded Area
★★★☆☆: (+5)-Yang, Negative 8 YY
★★★★★: Why-Why? Fog of War:
★☆☆☆☆: Erica 12, Erica 17
★★☆☆☆: It's What You Do in the Dark That Puts You in the Light, Find It All, What the Fog?, Erica 20
★★★☆☆: Broken Flashlight in the Dark Pencil Puzzle/Sudoku Hybrid:
★★☆☆☆: Masyu (Short) Sudoku
★★★☆☆: Tetromino Sudoku
Various Puzzles:
★☆☆☆☆: Blown Fuses in Electrical Installation, Let Me Introduce Myself, French Wrench
★★☆☆☆: Symmetrical Fan, Night Club, Important Hour on the Clock, What Was the Sum Again?, Disgroup Joints, 10-Arrows, Antiking Dutch Skyscrapers
★★★☆☆: Cops & Robbers, Positive Symmetry, Doppelgänger Killer 1-25
★★★★☆: Liars. Liars Everywhere.
Lösungscode: Eighth (8th) column of the grid from top to bottom (with the symbol "/" marking borders between shaded and unshaded cells, e.g., 123/4/5/67/89).
Kommentare
am 6. Mai 2026, 10:51 Uhr von SpringPeonies
I don't really understand this part:
Values: A value of a shaded cell equals its digit increased by the number of (up to 8) surrounding unshaded cells; a value of an unshaded cell equals its digit.
So how do i determine surrounding cells, like chess king move away from a cell or how many cells it can "see"(before it gets to next shaded cell along the row/column)?
SK: Surrounding cells are the immediate neighbours, so you can imagine 3x3 box centered on each shaded cell, and we are checking how many of those cells are unshaded.
(Thank you for the answer it makes sense now)
am 1. Dezember 2025, 17:19 Uhr von War
Excellent puzzle! Great break in logic, and very smooth mid-late puzzle tricks+math. Thanks for setting!
am 28. November 2025, 21:29 Uhr von Gnosis66
Very difficult path at first, but it was brilliant and led to some very satisfying “aha” moments.
am 24. November 2025, 17:38 Uhr von kublai
Hard to crack, but ooh when it cracks. I had a bit of a gollum moment there cackling with glee when I saw the path. Thanks for a great puzzle!
am 22. November 2025, 22:46 Uhr von ymhsbmbesitwf
for me it was indeed very hard. it immediately feels like certain things want to happen - it took a long while to understand why and how. really cool
