Nonogram is a logic puzzle where numbers along the rows and columns tell you which cells to fill, and the filled cells turn out to be a picture. This version runs free in your browser with no download and no signup: you start on 5x5 grids that hide a heart, a smiley or an arrow, move up to 10x10 pictures, and then keep going on larger mystery grids. If you like Sudoku but want something where the payoff is visual, this is the closest thing to it.
What the numbers mean: reading nonogram clues
Every number is the length of one unbroken run of filled cells in that row or column, and the numbers are listed in the order those runs appear — left to right for rows, top to bottom for columns. Between any two runs there must be at least one empty cell. So in a 10-wide row, the clue "4 3" means four filled cells in a row, then a gap of one or more, then three filled cells. The clue "1 1" means two single filled cells that are definitely not touching. A row with the clue "0" is completely empty, and in a 5-wide row the clue "5" fills every cell — those are your free moves, take them first.
What the clue does not tell you is where the runs sit. That is the whole puzzle. But you can immediately work out how much freedom a line has by adding the numbers together plus one gap for each pair of numbers, then subtracting from the line width. In a 10-wide row with clues "3 1 4", that is 3 + 1 + 4 = 8 filled cells plus 2 mandatory gaps = 10, exactly the width — so the row has zero slack and you can fill it in completely right now, with no other information at all. The same clues in a 12-wide row leave 2 cells of slack, meaning each run can slide at most two cells from its leftmost position.
That slack number is the one thing worth calculating on every line before you touch a cell. Lines with slack 0 are solved instantly, lines with slack 1 or 2 give you large guaranteed blocks, and lines with slack 6 tell you almost nothing yet, so skip them. In this game each row and column clue changes state the moment your line matches it exactly, which is a useful sanity check — if a clue you thought was finished has not registered as done, the runs are the right lengths in the wrong order, or a gap is missing.
Your first move on a blank grid: the overlap trick
On a blank grid, the technique that gets you started is called simple boxes, or just the overlap. Take a single run of length k in a line of width N. Slide it as far left as it goes, then as far right as it goes, and shade the cells that are covered both times. Those cells are filled in every possible arrangement, so they are certain. The arithmetic is 2k − N: a run of 8 in a 10-wide line gives 2(8) − 10 = 6 guaranteed cells in the middle. A clue of 4 in a 5-wide row gives 3. A clue of 3 in a 5-wide row gives exactly 1 — the centre cell. Anything where the clue is more than half the line length produces something.
With several numbers in a line, work with slack instead. Push all the runs as far left as they will go, then as far right as they will go, and any run longer than the slack overlaps itself. Concretely: clues "5 3" in a 10-wide row need 5 + 1 + 3 = 9 cells, so slack is 1, and both runs overlap themselves by 4 and 2 cells respectively — you have six certain cells before making a single deduction about the picture.
So the opening routine is: scan all rows and columns, note the biggest numbers and the tightest lines, and run the overlap on each of them. On a 5x5 grid look for any clue of 3, 4 or 5. On a 10x10 look for 6 and above, and for lines whose numbers nearly fill the width. Fill those cells, and the moment you place a filled cell you have new information in the crossing line — that is where the puzzle starts to unravel. Never begin by guessing at the picture: the picture is the reward, not the method.
Stuck with no obvious moves? Work down this ladder
First, punctuate. Whenever a run is finished at its correct length, put an X on the cells either side of it, and when a whole line matches its clue, X out every remaining cell in that line. Most people get stuck because they only mark filled cells and leave the empties blank, which throws away half the information they have already earned. Use Mark mode for this — those X cells are what makes the next three techniques work.
Second, glue to the edges. If a filled cell sits in the first cell of a row and the first clue is 5, that run must span cells 1 through 5 — there is nowhere else for it to start. The same works against an X: a filled cell immediately to the right of a blocked-off region anchors the run just like a border does. Third, force. An X splits a line into segments; try dropping each clue into each segment in order, and any segment shorter than the smallest remaining clue can be crossed out entirely. A gap of 2 cells is useless to a clue of 3, so fill it with X marks and watch that clue get pushed elsewhere.
Fourth, and this is the one people forget: after you finish any line, immediately re-check every crossing line it touches. New filled cells and new X marks change the slack in those lines, and re-running the overlap on them is where the chain reaction comes from. Fifth, count backwards from the far end for the last clue in a line — the arithmetic is easier from the right edge than from the left. Only after all of that, use contradiction: find a run with just two possible positions, assume one, push the consequences three or four lines out, and see if some line becomes impossible to satisfy. Nothing here penalises a wrong fill and there is no clock, so a test branch costs only your time. Tap a filled cell again to clear it and back out.
Nonogram, Picross, Hanjie, Griddlers — same puzzle, different names
The puzzle dates to 1987, when Japanese graphics editor Non Ishida won a Tokyo competition with grid pictures made from illuminated skyscraper windows. Tetsuya Nishio invented essentially the same puzzle independently and published his own version. The name "nonogram" came later from British puzzle collector James Dalgety, who mashed "Non" from Ishida's name with "gram" from diagram. So the word is a person's name, not a Greek root.
Everything else is branding. Picross is Nintendo's trademark, short for picture crossword, which is why the Game Boy and 3DS titles are called Mario's Picross and Picross 3D rather than nonogram. Griddlers was chosen by Sunday Telegraph readers in a 1998 vote. Hanjie, Pic-a-Pix, Paint by Numbers, Oekaki-Logic and Japanese Crossword all refer to the same thing, the last being the usual name across Eastern Europe.
The rules are identical under all of those names, so any technique you learn here transfers directly to a Picross cartridge or a newspaper Hanjie. The only real divergences are cosmetic conventions: some publishers put clues on the right and bottom instead of the left and top, and some use dots rather than X marks for known-empty cells. If someone tells you Picross and nonogram are different puzzles, they are describing two products, not two rule sets.
Do you need to be good at maths? Nonograms vs Sudoku and Minesweeper
The heaviest arithmetic in a nonogram is adding a handful of numbers under 20 and subtracting the result from the grid width. That is it. What the puzzle actually trains is constraint propagation: taking a partial fact, pushing it into a crossing line, and seeing what becomes forced. It is closer to reading a train timetable than to doing algebra, and plenty of strong solvers never write a single sum down — they eyeball the overlap by sliding the run mentally.
Compared to Sudoku, the difference is in the kind of information you get. A Sudoku constraint is exclusion — this digit already appears in the box, so it cannot go here. A nonogram constraint is positional and ordered, which means you regularly learn that a cell is filled without yet knowing which run it belongs to. That partial knowledge is unusual and is why Sudoku solvers often feel briefly lost on their first grid. Compared to Minesweeper, the difference is guessing: Minesweeper genuinely produces 50/50 positions where no deduction exists and you have to flip a coin, whereas a properly constructed nonogram with a unique solution is solvable end to end by logic alone.
For kids, a 5x5 grid is a reasonable first logic puzzle at around age seven. The largest possible clue is 5, the overlap rule can be demonstrated in thirty seconds by sliding a strip of paper, and mistakes are self-correcting because the emerging picture visibly goes wrong. As for the brain-training angle: solving nonograms makes you better at solving nonograms, and there is no good evidence that it makes you sharper at unrelated tasks. It is a clean, honest logic workout, which is enough.
Sizes, difficulty and variants: from 5x5 to colour nonograms
This game opens with ten 5x5 puzzles hiding named pictures — a heart, a diamond, an hourglass, a smiley, an arrow — then moves to ten 10x10 pictures including a rocket, a ghost, a crown and a lightning bolt. After those twenty, it keeps generating fresh grids and cycles through 5x5, 10x10 and 15x15 sizes so the difficulty keeps stepping up. There is no timer. Once you know the overlap rule, a 5x5 takes well under a minute, a 10x10 usually runs 3 to 8 minutes, and a 15x15 is more like 10 to 20. The 25x25 and 50x50 monsters you find in puzzle magazines are hour-plus sessions and are usually solved a region at a time.
Scoring is per grid solved: 125 points for a 5x5, 150 for a 10x10, 175 for a 15x15. Your best score is stored in your own browser, so the way to beat it is to keep chaining solves in one continuous run rather than restarting after each picture. There are no accounts and nothing is uploaded — clearing your browser data clears the record with it.
One thing worth knowing about multi-solution grids: puzzle designers deliberately construct their pictures so exactly one arrangement fits the clues, but an arbitrary pattern often does not have that property. The classic minimal example is a 2x2 grid where every clue is 1 — the two diagonals both satisfy it. This game checks your grid against the clues rather than against one stored answer, so on a generated puzzle any arrangement that satisfies every row and column is accepted; on the hand-made picture levels it snaps to the intended image when you finish. Colour nonograms are a separate variant you will meet elsewhere, where the clue numbers are coloured and two runs of different colours need no gap between them, so a blue 2 next to a red 3 can be five consecutive cells. This game is black-and-white only.
Questions people ask
Is it really free, and do I need to download or sign up for anything?
Yes, it is free, and it runs entirely in your browser — no download, no install, no account. Open the page and the first 5x5 grid is already there. There is nothing to register and no email required.
Do I have to use the X / Mark mode, or can I just fill cells?
You can win without it, but you will get stuck far more often. The X marks record which cells you have proved empty, and techniques like forcing and edge-gluing depend on those marks to split a line into segments. Switch to Mark mode and X out the cells either side of every completed run and every finished line — it costs a few seconds and unlocks most of the deductions that come next.
Can I get stuck in a position where I have to guess?
On the hand-made picture levels, no — they are solvable by logic all the way through. On the randomly generated grids after level 20, a pattern can sometimes admit more than one valid arrangement, in which case any arrangement that satisfies every row and column clue is accepted as a win. If you feel stuck earlier than that, it is almost always because a crossing line has new information you have not re-checked yet.
How long does one puzzle take?
A 5x5 takes under a minute once the overlap rule is second nature. A 10x10 is typically 3 to 8 minutes, and a 15x15 is roughly 10 to 20. There is no timer and nothing runs out, so you can leave a grid half-solved while you think.
Does my score save, and is it shared with anyone?
Your best score is stored locally in your own browser and shown on the results screen when you finish a run. It is not tied to an account and not sent anywhere, so it will not follow you to another device, and clearing your browser data will reset it. Each grid you solve is worth 125, 150 or 175 points depending on its size, so long unbroken runs beat frequent restarts.
How to play Nonogram
- Each number is a run of filled cells in that row or column, in order. “1 1” means two separate filled cells with a gap.
- Tap to fill a cell; use ✕ Mark mode to note cells that stay empty.
- Satisfy every row and column clue to reveal the hidden picture.
Nonogram is free to play online at Trivio — no download, no signup, works on desktop and mobile. Your best score is saved in your browser.