Twilight Cave Sudoku
(Published on 27. July 2022, 08:54 by PixelPlucker)
Twilight Cave is a variant of Cave in which number clues may be shaded and, if so, they indicate the size of the group of connected shaded cells they are part of. An example can be found on page 48 of the WPC 2019 Instruction Booklet.
Rules:
Normal Sudoku rules apply.
In addition, shade some cells such that every orthogonally connected group of shaded cells joins to the edge of the grid, and all unshaded cells form one orthogonally connected area — the “cave”.
A number clue in an unshaded cell tells you the sum of the digits that can be “seen” in the cave from this cell in all horizontal and vertical directions, including the digit in the clued cell itself. Shaded cells block the view. Digits may not repeat within this sum (that is, within the field of vision of an unshaded number clue).
A number clue in a shaded cell tells you the sum of the digits in its orthogonally connected group. Digits may not repeat within any orthogonally connected group of shaded cells, even if it does not contain any number clues.
Example (6x6):
The puzzle:
Link for online solving: Penpa+
(Solution check requires all digits to be filled, as well as for all shaded cells to be correctly filled in using light grey, grey, or dark grey.)
Setter's preface:
This puzzle is quite possibly my hardest and most intricate creation so far. It is constructed in a very particular style which may not appeal to all tastes, but I have worked hard to ensure that the puzzle can be solved through logical deduction alone. Good luck!
Solution code: Row 5 and column 8 (18 digits in total)
Comments
on 1. August 2022, 22:51 by lerroyy
Really nice puzzle! Incredible that the grid is symmetrical with the clues.
on 1. August 2022, 18:13 by Jesper
Extremely challenging but also very rewarding, thanks!
on 29. July 2022, 01:30 by Niverio
Absolutely, monstrously brutal.
on 28. July 2022, 09:51 by Phistomefel
So far, I have solved the example puzzle and I have to say, this is top-notch. I'm very much looking forward to solving the actual puzzle, albeit with some trepidation after reading the comments.
on 28. July 2022, 03:20 by RJBlarmo
Extremely difficult puzzle from start to finish, really enjoyed it.
on 28. July 2022, 00:58 by the_cogito
Very cool start. Very hard end.
on 27. July 2022, 20:44 by henrypijames
Another puzzle where I wandered forever in the wilderness before getting any idea of where to even begin.
on 27. July 2022, 18:05 by polar
Tough puzzle with lots of beautiful deductions. Very enjoyable solve - thanks :)
on 27. July 2022, 16:22 by abed hawila
Mindblowing puzzle!
Very hard, but rich in rewarding "Logical" deductions.
Very well constructed, I loved it!
Thanks ;)
on 27. July 2022, 12:16 by Vebby
Very challenging yet very rewarding to solve. Some awesome logic woven into this one. I highly recommend getting acquainted with the ruleset via the example puzzle first.
on 27. July 2022, 08:59 by KNT
It was an absolute honor to be able to test this, hours of fun! It is so, so intricate and rewarding the whole way through. For the sake of your intellectual enrichment, pleasure, or both, please absolutely do not miss this puzzle!
