Jigsaw Sudoku FAQ

Jigsaw Sudoku (also called Loco Sudoku, Irregular Sudoku or Nonomino) is a logic puzzle on a 9x9 grid. Instead of nine square 3x3 boxes, the grid is divided into nine irregular, connected regions of nine cells each. You fill the grid so that every row, every column and every region contains the digits 1 to 9 exactly once.

Yes. jigsawsudoku.app is completely free and runs entirely in your browser. There is nothing to buy, download, or install, and there are no interruptive video ads, premium tiers, or paywalls. Open the page and a puzzle is already on the board.

No. The game is the website — a 100% browser-based build with no app store download and no sign-up. Your stats and your puzzle in progress are saved locally in your browser, so there is no login to manage.

Only the shape of the groups changes. Classic sudoku uses nine 3x3 boxes; jigsaw sudoku uses nine irregular regions. Rows and columns work exactly as before. Because regions can twist across the grid, you cannot rely on the familiar box patterns, and you have to check each cell against its row, column and region separately.

"Loco Sudoku" is a name some people use for jigsaw-style sudoku with wildly shaped regions ("loco" is Spanish for "crazy"). It follows the same rules as Jigsaw Sudoku here: 1 to 9 once in each row, column and irregular region. You can play it on this site under the Jigsaw Sudoku name.

Select an empty cell and enter a digit from 1 to 9. A digit may appear only once in its row, once in its column and once in its coloured region. Use the bold given digits as your starting clues, deduce the rest, and the puzzle is solved when the whole grid is filled correctly. Pencil notes, undo and hints are available if you get stuck.

There are three: Easy (38 given digits), Medium (31) and Hard (25). Fewer givens mean more deduction and more use of pencil notes. The level is set by how many digits start on the board, and stats are tracked separately for each level.

A digit that does not match the solution turns red at once and adds one to the mistake counter; there is no game over, and you can undo or erase it. A hint fills in the correct digit for the selected cell (or a random unsolved cell if none is selected). Best times are recorded only for solves that used no hints.

Click or tap a cell, then click or tap a number. On a keyboard, 1–9 enter a digit, arrow keys move the selection, Backspace or Delete erases, N toggles pencil notes, U undoes, H gives a hint, Escape deselects and M toggles sound.

Turn on Notes and the number pad toggles small candidate digits in the selected empty cell instead of filling it. When you place a correct digit, that digit is automatically cleared from the notes of every cell in the same row, column and region.

You can erase or overwrite a digit that is wrong. Given digits and digits that match the solution are locked, so you cannot accidentally undo a correct move. Undo also steps back through your moves without limit.

Nine seed cells are chosen at random and grown outward, one neighbouring cell at a time, until each region has nine connected cells. The generator then finds a valid solution for that layout and removes digits while the puzzle stays unique. Layouts that cannot be solved are discarded and regenerated.

It feels different rather than strictly harder. Familiar box-based shortcuts no longer apply, so beginners often find the first few puzzles slower. Once you learn to read the region shapes, Easy jigsaw puzzles are comparable to Easy classic ones, and Hard ones reward the same techniques: singles, pairs, and region-and-line overlaps.

Yes. Each puzzle is generated on your device, then digits are removed one at a time while a solver checks that the grid still has exactly one solution. Every puzzle can therefore be solved by logic alone, without guessing.

Sweep one digit at a time across the whole board, start with the region, row or column that has the fewest empty cells, and use pencil notes only in cramped cells. Learn the region-and-line overlap: when a digit is confined to the part of a region that lies in one row, it cannot appear elsewhere in that row. The tips page walks through each technique.

No. Every puzzle has one valid solution. If you feel stuck it is a missed deduction, not a broken grid. Look for a digit that fits only one place in a region, a pair of cells with the same two candidates, or a region-and-line overlap. You can also use a hint.

The current streak counts consecutive solves at one level. Starting a new puzzle after you have begun the current one, or switching level mid-puzzle, counts as an abandoned game and resets that level’s streak to zero. Your longest streak is kept separately.

Yes. Your puzzle in progress (including notes and the timer), plus your solved count, best times and streaks for each level, are saved locally in your browser. Refresh the page and you carry on where you stopped. Nothing is sent to a server, so a different phone, a new browser profile, or cleared site data looks like a fresh start.

Yes. The board and the number pad fit above the fold on a phone in portrait. Tap a cell, then tap a digit. Notes, undo, erase, hint and new-puzzle buttons sit right under the board, and dealing a new puzzle is instant with no page reload.

The game needs a connection to load the page the first time. After that, your browser may keep the tab playable without a network, but there is no dedicated offline app or installer.

Open Stats with the chart icon above the board and use Reset stats, then confirm with the second tap. That clears solved counts, best times and streaks for all levels on this browser. It cannot be undone.

Any current browser with JavaScript: Chrome, Edge, Firefox and Safari on desktop, plus their mobile versions. If the board does not respond, update the browser, allow scripts for this site, and reload.