Sly ArcadeRead the boundary before you read the candidates.
An original lesson from the verified puzzle collection.
The rule
Each row, column and outlined nine-cell region contains 1–9 once. The irregular regions replace ordinary boxes.
Read the constraint
A thick outline encloses one nine-cell region, even when the region bends across where a familiar box would have ended. Row and column rules still apply. Ordinary 3 × 3 boxes do not.
Connect the candidates
Select a cell to see its related cells. Follow all nine region cells, then look for a digit with only one candidate position. Do not stop at a straight-looking edge.
Make a justified move
If all candidates for one digit in a region lie on a single row, the digit is locked into that row segment. It can be removed from the other cells in that row.
A real puzzle example
Open jigsaw-sudoku-001, then focus on r4c4. The explanation below is generated from this puzzle’s logical proof, without looking up its answer.
Reveal the explained next step
- Every other digit is excluded by the current units and constraint candidates.
The justified digit is 8.
Practice without a penalty
Use Notes to record options. Undo restores digits and notes together. Hints reveal attention, explanation and conclusion in separate steps. All 200 puzzles are open. A daily selection is a replay from the verified pool, with its own save.
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