Jigsaw Sudoku
Fill the grid so every row, every column and every outlined region holds the digits 1 to 9 exactly once. The regions are jigsaw shapes of nine cells, and every puzzle has one solution you can reach by logic alone.
How to play Jigsaw Sudoku
How to play
Tap a cell, then tap a number on the pad (or type 1 to 9). Each digit may appear only once in every row, every column and every region. Tap the same number again, or Erase, to clear a cell. Turn on Notes (or press N) to pencil in candidates; placing a digit removes matching notes from the cells it sees.
Reading the regions
Each region is drawn with a thick border, filled with its own light pattern (plain, dots, stripes or lines, never the same as a region next to it) and labelled with a letter from A to I in its first cell. Hints name regions by these letters.
The law of leftovers
One row holds each digit once, and so does one region. Take a row and the region that overlaps it most: once you leave out the cells they share, the cells of the row outside the region must hold the same digits as the cells of the region outside the row. The same works for two, three or four rows or columns and as many regions.
Levels and hints
Levels are set by the hardest step a logical solver needs. Gentle needs only singles. Moderate adds pointing (a region whose digit must sit in one row or column), line/region reductions and pairs. Tough needs the law of leftovers, or triples, X-wings, XY-wings or swordfish. Hint shows the next step, names it and explains it in one sentence.
Questions
What is Jigsaw Sudoku?
Jigsaw Sudoku, also called irregular Sudoku, is Sudoku where the nine 3×3 boxes are replaced by nine irregular regions of nine cells. Every row, column and region must hold the digits 1 to 9 once.
How is Jigsaw Sudoku different from normal Sudoku?
The rules are the same, but the regions wind across rows and columns. That makes some familiar patterns rarer and adds a new one, the law of leftovers, which compares the cells a row and a region don’t share.
What is the law of leftovers?
A set of rows holds each digit as many times as there are rows, and so does a set of the same number of regions. Leave out the cells they share and the leftover cells on each side hold exactly the same digits, so a digit that one side can’t hold is ruled out on the other.
Does every Jigsaw Sudoku here have exactly one solution?
Yes. Every puzzle was checked by a solution counter that found exactly one solution, and finished by a logical solver at its level, so you never need to guess.
Is there a daily Jigsaw Sudoku?
Yes. The daily puzzle is a Moderate Jigsaw Sudoku that is the same for everyone and changes at midnight UTC.