Jigsaw Sudoku Strategy: 5 Techniques
The odd shapes are the point: they create forcing patterns that boxes can't. New here? Read the rules first.
1. Read the shapes first
Before placing anything, trace each region. Note which regions stay inside a band of three rows and which spill out; that's where the special techniques live.
2. The law of leftovers
Take the top three rows. Some regions lie wholly inside them; a few cells of other regions poke in, and a few cells of the inside regions poke out. The cells poking in hold exactly the same set of digits as the cells poking out. With one cell each way, that's a forced equality.
3. Where a region meets a row
If a region has only two cells in a row, those two cells share the digits that the rest of the row can't take from them. Often a digit missing from the row must sit in one of the region's cells.
4. Cells in the same row and region
Two cells in the same row and the same region see all the same units. If their candidates are the same pair, nothing else in that row or region can hold those two digits.
5. Then plain sudoku
Naked and hidden singles, pairs and pointing work exactly as before; the region is just a strangely shaped box. When the jigsaw tricks run dry, go back to basics.
Frequently asked questions
What is the law of leftovers?
Take any few full rows. They contain each digit the same number of times as the regions lying entirely inside them. The cells that poke out of those rows and the cells that poke in must therefore hold the same digits.
Last updated 2026-10-20