Carpenter's square: Sashigane sudoku
(Published on 4. January 2026, 20:18 by Killer Joe)
Hello.
Normal sudoku rules apply.
Sashigane: Fill the grid entirely with L-shaped regions that are one cell wide. Digits cannot repeat within such region and each region contains at least one clue type.
Arrow cells are both bitclocks and region size counters.
Arrow cells containing an even digit sit at the end of an L-shaped region and indicate the size of its region.
Arrow cells containing an odd digit sit at the bend of an L-shaped region and indicate the size of its region.
A digit in a circle indicates the size of its region.
A digit in a square counts the amount of its own region cells it sees in all directions including itself.
Circles and squares can be located anywhere along the L-shape.
Bitclocks:
Each BitClock consists of an arrow cell and the four orthogonally adjacent cells surrounding it.
The digit in the arrow cell encodes the parities (Odd/Even) of those four neighbouring cells.
Even digit = ON (E)
Odd digit = OFF (O)
Each digit corresponds to a specific 4-bit parity code, read left to right in the table below.
The arrow points to the first bit of the code (read from left to right), and the code is applied clockwise around the four adjacent cells.
Example: If the arrow cell contains 3, its code is OOEE.
Starting from the direction the arrow points and moving clockwise, the four neighbouring cells must be Odd, Odd, Even, Even.
*For BitClocks touching the grid edge: cells outside the grid are treated as having parity determined by their row or column index. Cells outside odd numbered rows and columns are odd, cells outside even numbered rows and columns are even.
These outer cells are never filled. The outer border is only used for parity reference and marking.
Have fun.
Digit Codes:
1 → OOOE
2 → OOEO
3 → OOEE
4 → OEOO
5 → OEOE
6 → OEEO
7 → OEEE
8 → EOOO
9 → EOOE
Solution code: Row 9, first 6 digits.
Comments
on 11. January 2026, 03:35 by firespire
Solved this days ago so thought I best add to the ratings but it's not fresh in my mind how I solved it.
I'm weak solver and use answer-check like I'm doing a fog of war but got through this when some 1/2 star difficulty ones on here I have to give up on.
Kept my attention to complete so that's a good sign.
I like that is just counting rather than mathsy but seeing Simon on Cracking the Cryptic Youtube do Bitclocks as an on off sum of digits 8 4 2 1 has helped as I didn't need need to refer to the table like I have before, I know nothing of binary.
He would breeze through this, a more relaxing watch than Sudokus that need mathematical equations to solve. He did you Bits and Nibbles one which was too complex for me. This and your Chaos Construction versions are more my kind of thing.
Looks daunting, turned out fine but a weak solver like myself requires time and answer check button use.
If I remember is was more like a jigsaw puzzle, bitclocks played less of a part than what I was expecting.
-Thanks for your comment. Clicking the answer check is fine. I do that all the time even when I'm test solving my own puzzles. I agree that this feels more like a jigsaw puzzle. The bitclocks are not the main stars of the show. The sashigane is the main star. Grts Jonesy.
on 6. January 2026, 12:15 by bboom
I like the logic and the flow of the puzzle.
The ruleset complexity is pretty high though, in the sense that there are a lot of puzzle-specific rules to remember about where each kind of element can go in an L-shape, and what they are counting.
I still enjoyed the puzzle so no big complaint, but if there is a way to make it work with fewer rules, or more visually intuitive rules, it would make it even better to me, and would make the puzzle approachable for a larger group of people.
on 5. January 2026, 07:23 by Silverscree
I'm enjoying these bit clocks! They are much less confusing than I initially expected them to be.
-Thank you ! Glad to hear. Grts Jonesy.
