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Hidden Hierarchy - A Kropki Sudoku

(Published on 5. September 2026, 17:07 by TheAuthenticCheese)

Hidden Hierarchy - A Kropki Sudoku

  1. Sudoku: Place the digits 1-9 once each in every row, column, and 3x3 box.
  2. Anti-Knight: Cells a knight’s move away from each other cannot contain the same digit.
  3. Domino Clues:
    1. If a domino (pair of orthogonally adjacent cells) have a symbol of any kind between them, that domino is considered “clued.”
    2. Each type of clue has been placed in a hierarchy of ranks.  The hierarchy is to be deduced by the solver.
    3. A clued domino will always display the highest rank clue possible (even if other clues would otherwise be valid).
    4. An “un-clued” domino may have any two digits, even if they would satisfy the conditions of a possible type of clue.


Example:

  • Let’s say the White Kropki Dot was higher up the hierarchy than the Black Dot.
  • A domino with a black dot between its two cells could then contain the digits 2 and 4, but could not contain 1 and 2 because a 1-2 domino would also satisfy the White Kropki rule (a higher rank clue).
  • A domino with no clue could contain a 1-2, a 2-4, or any other pair of digits, even though these pairings could satisfy the conditions of a type of clue. (Unclued = Unrestricted).

Clue Types (Alphabetically Ordered - Again, the order of rankings is to be deduced):

  1. Black Kropki - If two digits are separated by a black dot, one is 2 times the other.
  2. Dutch Dots - If two digits are separated by an Orange dot, they must differ by at least 4.
  3. German Dots - If two digits are separated by a green dot, they must differ by at least 5. 
  4. Gray Kropki - If two digits are separated by a gray dot, one is 3 times the other.
  5. Parity Dots - If two digits are separated by a red dot, they must be of different parity (one even and one odd).
  6. V - Digits separated by a V sum to 5.
  7. White Kropki - Digits separated by a white dot are consecutive.
  8. X - Digits separated by an X sum to 10.
 

Play on SudokuPad

Solution code: Using the Key in the Sudokupad Completion message, list the order of the clues in the Hierarchy from highest rank to lowest.

Last changed on on 5. September 2026, 20:52

Solved by Mad-Tyas, kangaroo, Saltensity
Full list

Comments

on 8. September 2026, 07:01 by TheAuthenticCheese
@Mad-Tyas

Thanks for the feedback! I thats a good point about so few registered solves. I ended up doing that because after setting and testing the puzzle I realized it was possible, indeed even likely, that solvers could fill the grid without fully discerning the hierarchy. However, it was so key to the original puzzle concept I wanted to add that last deduction as a final challenge. I would be fascinated to see a more experienced setter have a go at setting a puzzle with both an unambiguous hierarchy, and one that needed to be deduced in order to finish the solve.

on 5. September 2026, 20:52 by TheAuthenticCheese
Fixed a Rules Formatting

on 5. September 2026, 18:33 by Saltensity
Very solid puzzle, can be very smooth if you understand the rules well! Still struggled a bit at the SOLUTION CODE xD

Difficulty:3
Rating:N/A
Solved:3 times
Observed:0 times
ID:000UQA

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