About Jigsaw Sudoku
Jigsaw Sudoku, also called irregular sudoku, keeps the rows and columns of the classic game and throws away the 3×3 boxes. In their place are nine irregular regions of nine squares each, outlined and coloured on the board. Every row, column and region must contain 1 to 9 exactly once.
How to play Jigsaw Sudoku
- Every row and column contains 1 to 9 exactly once.
- Every outlined region contains 1 to 9 exactly once.
- The ordinary 3×3 boxes do not apply. Only the coloured regions count.
What changes
Classic sudoku trains your eye to work in boxes. Jigsaw breaks that habit: a region can stretch across three rows in a crooked line, so the box you are used to checking simply is not there. The first few puzzles feel harder than they are.
The technique that helps most is counting. Each region and each row holds exactly nine digits, so when a region pokes one square out of a set of rows, compare what the region needs with what those rows still need. The square that sticks out often has only one possible digit.
Difficulty
Easy to Expert changes how many digits you start with, from 38 on Easy to 25 on Expert. Region shapes are new for every puzzle, and long, winding regions are usually harder to read than compact ones.
Controls
- Select a square, then use the number pad or keyboard.
- N toggles notes, Backspace erases, H gives a hint, U or Ctrl/Cmd+Z undoes.
- Progress and notes are saved for each variant separately.
Scoring
| Level | Base | Speed bonus, up to | Per mistake | Per hint |
|---|---|---|---|---|
| Easy | 1,000 | 250 | −100 | −250 |
| Medium | 2,000 | 500 | −200 | −500 |
| Hard | 3,500 | 875 | −350 | −875 |
| Expert | 5,000 | 1,250 | −500 | −1,250 |
Only fully solved puzzles are ranked. Your score is the difficulty base plus a speed bonus of at most 25% of that base. The bonus falls by 0.5 points per elapsed second, rounded to the nearest whole point, and never below zero. Each mistake deducts 10% of the base; each hint deducts 25%. A solved puzzle always earns at least 10% of its base. Undo does not refund time, mistakes or hints. Each Sudoku variant has its own leaderboard. Existing scores remain on the same boards; new solves use this formula.
