Cavernous Japanese Sum: Deconstruction (9x9)
(Published on 21. November 2025, 15:00 by Playmaker6174)
While confirming some more assurance on my current big project, here's a puzzle that acts as another proof of concept for one of my interesting crafted ideas in the past.
As some might have noticed, my puzzle outputs in this year 2025 don't really follow a specific pattern, and that's because I've been constantly expanding my setting style and experimenting with bunch of different puzzle ideas I'd crafted over time.
Some didn't turn out as well as how I expected, some even exceeded such, then there're a handful list of ideas that are rather promising and give me some hopes for some revisit in the (near) future, and I think the following puzzle here may get to join that list too.
The idea of this one comes after revisiting bunch of Japanese Sum puzzles and Cave puzzles I'd solved. I think it's quite easy to make wrong assumptions in the middle, but going slow and steady will help a lot for the thought process in here.
Also, if this gets enough interests then I may try a bigger version of this (with maybe some minor improvement) in the future. For now, please do enjoy the puzzle!
Rules:
- In the 9x9 grid, exactly nine empty cells must be marked so that one empty cell must be marked in every row and every column. Additionally, divide all of the non-empty cells into nine orthogonally connected regions so that every region contains exactly eight cells.
- Every non-empty cell contains the number that’s equal to the total amount of cells seen horizontally and vertically from that cell’s perspective, including itself, where region borders and the 9x9 grid perimeter block the visions.
- A circle clue outside a row/column corresponds to exactly one continuous group of cells that share the same region in that row/column, and its value shows the sum of that group, if given.
- The correct order of the clues is from left to right for the row and from top to bottom for the column. It's possible the same region can represent multiple groups in a row/column.
- In this puzzle, a question mark (?) can represent any single digit from 0-9, but a single digit clue cannot be zero (0).
Setter's note: Here's an example image below to showcase how the concept works (5x5 grid, with five regions containing four cells each).
Puzzle: Penpa plus - Sudokupad
The answer check in penpa link will activate once all of the non-empty cells are correctly filled and also the region borders are correctly drawn (not counting the 9x9 grid perimeter). For now, good luck and have fun solving!
As some might have noticed, my puzzle outputs in this year 2025 don't really follow a specific pattern, and that's because I've been constantly expanding my setting style and experimenting with bunch of different puzzle ideas I'd crafted over time.
Some didn't turn out as well as how I expected, some even exceeded such, then there're a handful list of ideas that are rather promising and give me some hopes for some revisit in the (near) future, and I think the following puzzle here may get to join that list too.
The idea of this one comes after revisiting bunch of Japanese Sum puzzles and Cave puzzles I'd solved. I think it's quite easy to make wrong assumptions in the middle, but going slow and steady will help a lot for the thought process in here.
Also, if this gets enough interests then I may try a bigger version of this (with maybe some minor improvement) in the future. For now, please do enjoy the puzzle!
Rules:
- In the 9x9 grid, exactly nine empty cells must be marked so that one empty cell must be marked in every row and every column. Additionally, divide all of the non-empty cells into nine orthogonally connected regions so that every region contains exactly eight cells.
- Every non-empty cell contains the number that’s equal to the total amount of cells seen horizontally and vertically from that cell’s perspective, including itself, where region borders and the 9x9 grid perimeter block the visions.
- A circle clue outside a row/column corresponds to exactly one continuous group of cells that share the same region in that row/column, and its value shows the sum of that group, if given.
- The correct order of the clues is from left to right for the row and from top to bottom for the column. It's possible the same region can represent multiple groups in a row/column.
- In this puzzle, a question mark (?) can represent any single digit from 0-9, but a single digit clue cannot be zero (0).
Setter's note: Here's an example image below to showcase how the concept works (5x5 grid, with five regions containing four cells each).
Puzzle: Penpa plus - Sudokupad
The answer check in penpa link will activate once all of the non-empty cells are correctly filled and also the region borders are correctly drawn (not counting the 9x9 grid perimeter). For now, good luck and have fun solving!
Solution code: Enter the last row (row 9) from left to right - enter the corresponding number for each non-empty cell and enter the capital letter X for the empty cell.
Solved by MaizeGator, Jesper, tuturitu, Mr_tn, zakkai, MagnusJosefsson, puzzler05
Comments
on 25. November 2025, 13:28 by MagnusJosefsson
Fantastic puzzle, very original and interesting. Likely somewhat harder than 3* for most solvers (in my opinion), but very rewarding when you stick with it.
on 23. November 2025, 16:01 by Jesper
Enjoyed this new concept, thanks!
on 21. November 2025, 18:12 by MaizeGator
Super cool and weird puzzle. Logically probably 3*, but counting is hard and rewiring your brain to stop sudoku scanning is even harder.
