Normal sudoku rules apply.
Each digit from 1-9 is represented by a letter from A-I. You must determine
which letter represents which digit. You can use the register underneath the
grid for note-taking.
Regular quadruples: each digit in a circle must appear in one of the
4 cells surrounding the clue.
Self-indexing quadruples: an XYZW-clue outside a row or column
indicates that the cells at distances X, Y, Z, and W from the clue
contain an XYZW-quadruple.
Examples: A 2358-clue to the left of row 2
indicates that r2c2358 contain a 2358-quadruple; a 1467-clue underneath
column 8 indicates that r3469c8 contain a 1467-quadruple.
(Tooltip: the self-indexing quad clues are clickable cells. You can colour them or add corner marks if you wish)
This puzzle was loosely inspired by Quad Code by Marty Sears. It's very challenging, but there is a smooth solve path. Good luck!
Solution code: The digits in row 1, from left to right
on 6. September 2024, 09:03 by Pulsar
@dpatti 10 hours? Wow, I admire your tenacity, you deserve an award for that :-) I'm glad you enjoyed it. You can check the solution guide to see my own solve path. Thanks again!
on 6. September 2024, 06:41 by dpatti
This was, undoubtedly, my longest solve to date at just over 10 hours. I enjoyed slowly whittling it down, thanks for sharing!
on 19. August 2024, 23:27 by Pulsar
Fixed a typo in the title on SudokuPad, thank you @Fool on Hill for pointing it out. And thank you for solving and the kind words!
on 19. August 2024, 22:22 by Fool on Hill
What an interesting set of ideas ... great puzzle, but seriously hard ... I've not seen anything quite like it before.
Difficulty: | ![]() |
Rating: | N/A |
Solved: | 5 times |
Observed: | 5 times |
ID: | 000JF7 |
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