Sum-X-Sum [YYJ Pack]
(Published on 6. June 2026, 01:00 by yttrio)
This was originally created for the Yin Yang Journey puzzle pack. Links to previous puzzles in the pack are below:
Go Yin Yang
Through the Caverns
Sandwich Break
Staircase Serpent
Roman Negativity
Into Chaos
At Odds with Where to Go
Twin Yang
Balanced Whispers
Thermarrows
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.
Cells separated by a white dot are both unshaded, and their digits are consecutive.
Cells separated by a black dot are both shaded, and their digits have a ratio of 2:1.
Clues outside the grid are X-sum clues for shaded cells: they give the sum of the first N shaded cells in that row/column, where N is the digit in the first shaded cell that clue sees in its row/column.
Clues outside the grid also give the sum of all unshaded cells in that row/column.
6x6 Example:
The image below shows a sample 6x6 puzzle and solution with the same rule set.
Note: The example doesn't utilize any black dot clues.
Play the example in SudokuPad.
Solution code: Digits in shaded cells in row 6 (left to right) followed by digits in shaded cells in column 6 (top to bottom)
Comments
on 8. June 2026, 19:33 by DaniK
Another great addition to the series! many thanks :)
on 8. June 2026, 17:54 by DaniK
Another great addition to the series! many thanks :)
on 8. June 2026, 10:01 by Nemefish
I hit a few walls, but that usually made the "AHA" moments more resonant. I may not have found the intended path near the end but overall, a really fascinating challenge.
on 7. June 2026, 18:16 by HumanBirdsong
Very nice puzzle!
on 7. June 2026, 14:16 by pmays123
Lovely! Thanks
on 7. June 2026, 12:33 by marcmees
One of the nicest puzzles in this YksYJ pack. Than
on 7. June 2026, 11:59 by Donatello_86
Cool use of x-sums
on 6. June 2026, 22:25 by Exigus
Very cool mechanics. Thanks!
on 6. June 2026, 11:54 by Snookerfan
Excellent puzzle! Very nice interactions. Thanks
on 6. June 2026, 10:07 by Wuschel
Very nice, thank you!
on 6. June 2026, 09:46 by Piatato
Very smooth and fun, thanks!
on 6. June 2026, 04:34 by ArkansasJones
Any day there's a new YYJ puzzle from yttrio is a good day.
Very nice puzzle as always! I loved the logic to break in and get the shading going and the interplay between the shading and the X-sums was fantastic. I got stuck a bit toward the end of the shading, but that's definitely due to a skill issue not a problem with the puzzle.
on 6. June 2026, 04:32 by Elliott810
Absolutely brilliant puzzle! Thank you:)
