SudokuBoku

Jigsaw sudoku Irregular 9×9

The boxes are gone. In their place, nine snaking shapes — and a family of deductions that classic grids can never offer.

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Puzzle —
Rules
  • Fill every row, every column and every 3×3 box with the digits 1 to 9.
  • A digit can appear once in each of those — never twice.
  • There is exactly one solution, and logic alone will reach it.
  • Rows and columns each take the digits 1 to 9, once apiece.
  • The boxes are irregular shapes, drawn with the heavy outlines.
  • However a region bends, no digit repeats inside it.
  • The colour patches are cages; the small number is what a cage's digits add up to.
  • No digit repeats within a cage — nor in any row, column or 3×3 box.
  • There are no given digits: the sums alone pin down the whole grid.
  • Everything from classic applies: rows, columns and 3×3 boxes take 1 to 9.
  • The two tinted diagonals must each hold 1 to 9 exactly once as well.
  • All the classic constraints hold — rows, columns and 3×3 boxes take 1 to 9.
  • Each of the four shaded windows must also contain 1 to 9 exactly once.
  • The windows sit a step in from the corners, overlapping four boxes apiece.
  • Rows, columns and 3×3 boxes work exactly as they always have.
  • On top of that, two squares a chess knight's move apart may not hold the same digit.
  • Select a square and its knight partners are ringed with a dashed outline.
  • Every row, column and 3×3 box holds 1 to 9, exactly as in classic.
  • Along each grey path, digits strictly climb from the round bulb to the far end.
  • They don't have to be consecutive — each square just beats the one before it.
  • Rows, columns and 3×3 boxes take 1 to 9, exactly as in classic.
  • The digits along each arrow add up to the digit in the circle it comes from.
  • Digits may repeat along an arrow — as long as no row, column or box objects.
  • Fill every row, column and 3×3 box with the digits 1 to 9, as usual.
  • Between squares in the same box you'll find a sign; its point aims at the smaller digit.
  • Every comparison inside every box is shown — a hundred and eight of them.
  • The higher levels hand you fewer digits, not fewer signs. Expert gives you four.
  • Fill every row, column and 3×3 box with the digits 1 to 9, as usual.
  • A white dot between two squares means their digits differ by one.
  • A black dot means one digit is exactly double the other. 1 and 2 are both, and always show black.
  • A boundary with no dot is a clue too — those two digits are neither one apart nor double and half. Every boundary is marked or deliberately bare.
  • Expert hands you no digits at all. The dots and the gaps are the whole puzzle.
  • Fill every row, column and 3×3 box with the digits 1 to 9, as usual.
  • A square with a ring behind it holds an odd digit — 1, 3, 5, 7 or 9.
  • A square with a frame behind it holds an even one — 2, 4, 6 or 8.
  • Most squares are marked with neither, and those are genuinely unrestricted.
  • Every square switches to the fully marked board — one level, gentler than it looks, and two puzzles sharing a grid rather than one.
  • Every row, column and box holds five odd digits and four even ones — so once five squares of a house are known odd, the rest of it is even, marked or not.
  • Solve the 9×9 sudoku as usual — every row, column and box takes 1 to 9.
  • Ten ships are hidden on the same squares: one of four, two of three, three of two and four single squares.
  • Ships are straight, and no two of them touch — not even at a corner.
  • The numbers beside and below say how many ship squares each row and column holds.
  • A ship listed with digits sits on exactly those digits, in order — so the grid is your map.
  • Five 9×9 grids interlock: four corners and a centre, each corner sharing one 3×3 box with it.
  • Every grid obeys ordinary sudoku on its own — rows, columns and boxes each take 1 to 9 once.
  • A tinted box belongs to two grids at once, and only together do the five have one solution.
  • Fill every row, every column and every box with the digits 1 to 6.
  • The boxes are three squares wide and two tall.
  • Nothing repeats in any row, column or box.
  • Put 1, 2, 3 and 4 into each row, each column and each 2×2 box.
  • No digit may appear twice in any of them.
  • Every square can be worked out — no guessing needed.
Keyboard shortcuts
1–9
Place a digit, or toggle a pencil mark
Arrows
Move around the grid
N
Notes mode on or off
Backspace
Clear the square
Ctrl + Z
Undo · Ctrl + Y redo

Jigsaw puzzles for the printer

A pack of irregular grids, drawn as crisp vectors with the region borders inked heavy, built entirely on your own machine. Solving these on paper is its own pleasure — shading the shapes as they fill.

Difficulty

Three constraints, minus the one you lean on

A jigsaw grid — you'll also see it called squiggly, irregular, or nonomino sudoku — keeps two of classic sudoku's three promises. Rows still take 1 to 9. Columns still take 1 to 9. The third constraint no longer belongs to tidy three-by-three boxes: it belongs to nine interlocking shapes, each nine squares of connected territory, each needing all nine digits.

On paper that's a cosmetic swap. In practice it removes the crutch that carries most solvers through classic grids without their noticing. A box occupies exactly three rows and three columns, forever, and half of classic technique quietly depends on that regularity. A jigsaw region might lie along four rows and five columns, wrap around a neighbour, or run nearly the full height of the grid. Every cross-hatching habit you own has to be re-earned against a shape that's different in every puzzle.

Nine legal regions from one generated layout. The tinted shape climbs seven of the nine rows — geometry no box-trained reflex is prepared for.

The compensation is generous, though. Irregularity doesn't just take techniques away — it creates one.

The Law of Leftovers

Two coverings of the same ground

Take the top two rows of a jigsaw grid: eighteen squares, containing 1 to 9 twice over. Now take the two regions that mostly occupy those rows: also eighteen squares, also 1 to 9 twice over. The two collections aren't identical — a region pokes a square or two out of the band, and a foreign region pokes into it. But the digits in each collection are the same multiset, so everything the band and the regions have in common cancels.

Whatever sticks into the band must equal whatever sticks out of it.

The one-in, one-out move

The version worth training your eye for is the smallest one. One square inside the band that the covering regions don't own; one square outside it that they do. Those two squares are forced to hold the same digit — before you know what that digit is. The moment either end resolves, the other fills itself in, often somewhere your ordinary scanning would not have reached for another ten minutes.

Two tinted regions almost tile the top two rows: one band square isn't theirs, and one of their squares sits below it. The pair marked a must hold the same digit.

This kind of reasoning has no classic equivalent, and that's precisely because boxes are rectangular: any band of rows is tiled exactly by boxes, with nothing left over to reason about. It takes crooked regions to make leftovers exist.

Where to hunt for it

Work inward from the edges. Look at the top row alone, then the top two, then three, and the same from the bottom and both sides. At each band, ask how many squares spoil the fit between lines and regions. One spoiler each way is your move; none means the band is sealed and tells you nothing. The geometry never changes mid-solve, so this survey costs you one pass at the start and pays dividends for the whole game — and here, the hint button will point the pattern out by name when one is on the board.

What your classic instincts are worth here

Scanning must follow the shape

The classic reflex of striking a digit through three boxes at a time dies immediately — there is no longer any fixed relationship between a region and the lines that cross it. What replaces it is slower but sharper: pick a region, trace which rows and columns its squares actually touch, and cross off from there. Expect your first jigsaw solve to take half as long again as a classic grid of the same grade. That's not you; that's the terrain.

Locked candidates grow teeth

The interaction between a region and a line is where jigsaw quietly gets richer. In a classic box, a digit confined to one row of the box can occupy at most three squares. A snaking region might lay five or six of its squares along a single row — and when a digit's possibilities inside the region all fall on that row, it vanishes from the rest of the row at a stroke. The same logic runs in reverse when a row's remaining spots for a digit all sit inside one region. Both directions come up more often than on classic grids, and with bigger consequences.

Six squares of one region lie along the top row. When a digit's last places in that region are all up there, the row's other three squares lose it in one stroke.

What survives untouched

Anything built purely from rows and columns crosses over intact. An X-wing doesn't care what the regions look like; nor do naked or hidden pairs inside a line, nor the digit-with-one-home scan you use inside any single unit. Your foundations are safe. It's the box-shaped shortcuts, not the logic, that you're giving up.

Four levels, measured with the same ruler

Every jigsaw puzzle here is born in your browser: a fresh region layout is grown by repeatedly trading squares between neighbouring shapes (never letting one break in two), a full grid is built to fit it, and clues are removed only while exactly one solution provably remains. Then the result is graded the way everything on this site is graded — by replaying it with human techniques and recording the hardest one it forced.

Easy means naked singles carry you end to end. Medium brings in the hidden single. Hard is where pencil marks, locked candidates and the Law of Leftovers earn their keep, and Expert reaches for wings, fish and colouring. If a generated grid needs more than its level permits, it's thrown away before you ever see it — the label is a measurement, not a mood.

You'll notice there is no Evil or Extreme here. Those levels on the classic board are drawn from large curated banks that we've verified puzzle by puzzle, and no such banks exist for irregular layouts — each shape would need its own. Rather than relabel Expert and call it progress, the ladder stops where our honesty does. If you want the deep end today, it lives on the evil and extreme pages.

Reading and using this board

Seeing the shapes

Regions are drawn with the same heavy rule that marks boxes on the classic board, and selecting any square tints its whole region along with its row and column. When a shape's reach surprises you — and some of them reach a long way — a tap on one of its squares shows you everything it touches. The pencil-mark, undo and mistake behaviour is identical to every other board on the site, so nothing about the controls needs relearning.

A link that carries the shape

The share button under the grid copies a link holding both the clues and the region layout, so the person who opens it plays your exact puzzle — same shapes, same givens — with no account and no server copy that can expire. Their game and yours are saved separately, and the short code under the board identifies the puzzle-plus-shape pair if you'd rather quote it than send a link.

Taking it to paper

The pack builder above prints irregular grids with the boundaries drawn thick enough to follow in pencil light. Jigsaw works unusually well printed: tracing a region with your finger is easier on paper than on glass, and the answer key at the back reproduces each puzzle's layout, not just its digits.