Jigsaw Sudoku

What is Jigsaw Sudoku?

Jigsaw Sudoku is sudoku with its boxes cut free. The grid is still 9 by 9 and every row and every column still holds the digits 1 to 9 once, but the nine square boxes are replaced by nine irregular regions of nine cells each, fitted together like the pieces of a jigsaw. Every region must also hold each digit once. Bold walls trace the regions, and each one is washed in its own soft watercolour tint, so the shapes read at a glance.

Every grid has exactly one answer, reached by reasoning and never by guessing. There are three levels on the 9 by 9 grid, an easy 6 by 6 grid with six regions of six cells for a gentle start, and every day brings a new grid, the same for everyone.

How to play Jigsaw Sudoku

Tap a cell to select it, then tap a digit on the pad; tap the same digit again to take it out.

• Rows, columns, regions. Each digit appears once in every row, once in every column and once in every region. On the 6 by 6 grid the digits run from 1 to 6.
• Regions. A region is the shape inside the bold walls. The colour only helps the eye: the walls alone tell you where every region begins and ends.
• Highlights. The selected cell lights its row, its column and its region, and every cell holding the same digit.
• Mistakes. A digit that repeats one already in its row, column or region turns red.
• Notes. Turn on Notes to write small candidates in a cell; a digit you place disappears from the notes of its row, column and region. On a computer keyboard, the digit keys, arrow keys, N for notes, Backspace to erase and Ctrl+Z (or Cmd+Z) to undo all work.
• Undo. Undo takes back your last change, a digit or a note, as often as you like and at no cost.
• Score. Your score is the time to solve the grid, plus 30 seconds per hint. Each level has its own leaderboard.

Tips and strategy

1. Scan the odd shapes first. A region that stretches along one row or column often leaves a digit only one place to go in the line it crosses.
2. Regions and lines talk to each other. When every place left for a 7 inside a region lies in one row, that row's 7 is inside the region, so no other cell of the row can be a 7. It works the other way round too: when a row can only put its 7 inside one region, the rest of that region cannot hold a 7.
3. Look for pairs. When two cells of a row, column or region can only hold 4 and 8 between them, no other cell of that house can be a 4 or an 8.
4. Count what is missing. In a region with only three empty cells, write the three missing digits as notes and strike them out as rows and columns settle.
5. Use the hint to learn. A hint names the step it used, and outlines the region or line it read, so the next time you can spot the same step yourself.

Frequently asked questions

Is Jigsaw Sudoku free?

Yes. Like every game on Play, it runs free in your browser, with no download and no account.

Is it harder than classic sudoku?

The rules are the same, but irregular regions cross the rows and columns in new ways, so the familiar box patterns no longer apply. Many players find the region and line steps more varied than in classic sudoku.

What does a hint do?

It first fixes a wrong digit if there is one. Otherwise it fills in the cell that reasoning reaches next, and the line under the grid says why: the row, column or region that settles it, and the step it leaned on, if any. Each hint adds 30 seconds to your time.

What do the levels mean?

Easy 6×6 and Easy 9×9 are solved with singles alone: a cell with one digit left, or a digit with one place left. Medium always needs at least one step where a region and a line meet. Hard has fewer givens and always needs a pair or a triple, or a long run of region and line steps.

What is today's grid?

Every day everyone gets the same Medium grid, so times compare directly on the leaderboard.