Home›Guides›How to Play Nonograms
How to Play Nonograms (Picross): Reading the Clues
A nonogram looks like a crossword that lost all its words and kept only the numbers. There is a blank grid, a column of figures down the left, a row of figures across the top, and somewhere inside that grid a picture is hiding. The trick is that you never have to be clever or lucky to find it: every filled square is already decided by the clues, and your job is simply to read them in the right order. Once you learn how the numbers describe the picture, the grid turns into a quiet, satisfying chain of small certainties. This guide walks you through that, from what the clues actually mean to the handful of techniques that solve almost any board.
What a nonogram actually is
A nonogram - also sold as picross, hanjie, griddlers, and paint-by-numbers - is a grid of square cells that you either fill in or leave blank. When you are done, the filled cells form a small picture, like a heart, a cat, or a piece of fruit. You decide which cells to fill using only the number clues printed beside each row and above each column.
There is no arithmetic. The numbers are not sums to calculate; they are descriptions of where the filled cells go. And like Sudoku, a well-made nonogram has exactly one solution you can reach through logic alone. If you ever feel forced to flip a coin, there is almost always a square elsewhere on the board whose answer is already locked in.
How the number clues describe runs
This is the one idea that makes everything else click. Each clue is a list of numbers, and each number is the length of an unbroken run of filled cells in that line, listed in the order they appear.
- A clue of 5 on a row means one solid run of five filled cells, somewhere along that row.
- A clue of 2 1 means a run of two filled cells, then at least one empty cell, then a single filled cell - in that order, left to right (or top to bottom for columns).
- A clue of 1 1 1 means three lone filled cells, each separated from the next by one or more gaps.
Two rules are baked into that. The order is fixed: 2 1 is never the same as 1 2. And every separate number must have at least one empty cell between it and the next run - otherwise they would read as one longer run. So a clue of 2 1 on a five-wide row needs two cells, a gap, and one cell: four cells of content, leaving only one cell of slack to slide around. That slack, or the lack of it, is exactly what you exploit.
The handy sum. Add up a line's clue numbers, then add one for each gap between them. If that total equals the line's length, the line is completely determined - you can fill it straight across with no thinking. On a five-wide row, a clue of 2 1 needs 2 + 1 + 1 = 4 minimum, so there is wiggle room; but 3 1 needs 3 + 1 + 1 = 5, exactly the width, so it can only be filled one way.
Marking filled and marking empty
You are really tracking two kinds of certainty, not one. A cell you have proven must be filled gets coloured in. A cell you have proven must be empty gets an X (or a dot). Beginners often only fill cells and ignore the empties, and that is the single biggest reason boards stall.
- Fill a cell the moment you can prove it belongs to a run.
- Mark an X the moment you can prove a cell cannot be filled - because a run that already satisfies its clue closes off the rest of the line, or because no run could reach that far.
Those X-marks are not decoration. Every empty you mark shrinks where a remaining run can live, which often forces the next fill. A line is only "solved" when every cell is either filled or X'd - half-finished lines hide easy moves in plain sight.
The overlap technique
This is the most powerful single trick in nonograms, and the one to learn first. When a run is long compared to the space it can slide in, its two extreme positions still cover some of the same cells in the middle - and those shared cells must be filled no matter where the run actually sits.
Picture a row ten cells wide with a clue of 8. Push the run hard left and it covers cells 1 through 8; push it hard right and it covers cells 3 through 10. Both positions share cells 3 through 8, so those six cells are guaranteed filled before you know the run's exact home. To find the overlap: take the run length, subtract the slack (the line length minus the minimum the whole clue needs), and that many cells in the centre are forced.
The rule of thumb is simpler than the maths: any run longer than half its available space has a forced middle. Start every new board by scanning for the biggest clue in each row and column and claiming its overlap. Those first certain cells are the seeds the rest of the solution grows from.
Try it small. If overlap feels abstract, watch it on a tiny board where the whole row is visible at once. Mochi Pixel opens with 3×3 puzzles in its Berry world and only grows to 6×6 later, so a single oversized clue lights up its forced cells immediately - the perfect place to feel the technique before it has to scale.
Work the edges first
Lines that touch the edge of the grid give up the most information, because a run against a wall has nowhere to hide. If a row begins with the clue 4 and you already know cell 1 is filled, then cells 2, 3, and 4 are forced too - the run cannot start earlier than the wall, so it has only one position from that anchor.
- Find any line whose first run is anchored at an edge - by a filled cell at the wall, or by a long first run that cannot fit anywhere but flush against it.
- Fill that run completely, then X the gap after it so it cannot accidentally grow.
- Move to the opposite edge of the same line and repeat - the last clue number anchors against the far wall just as the first anchors against the near one.
Corners are especially generous: a corner cell belongs to both an edge row and an edge column at once, so proving it filled or empty pays off in two directions.
Let a completed line force its neighbours
Nonograms are solved by laddering between rows and columns, never by staring at one line in isolation. The instant you fill a cell in a row, it becomes a known fact in the column that crosses it - and that fact often forces a square further down the column, which forces the next row, and so on.
A finished line is the strongest gift of all. Once a row is solved, every filled cell in it anchors its column and every X confirms an empty. Sweep the crossing columns straight after completing any line: you will usually find a run that can now only sit in one place, or an empty stretch you can X out wholesale. This cross-checking - fill a row, update the columns, fill a column, update the rows - is the rhythm of the entire game.
A simple solving routine
Put the pieces together and you have a loop that cracks the vast majority of boards:
- Claim the overlaps. Scan every row and column for its biggest clue and fill the forced middle cells.
- Anchor the edges. Fill any run pinned against a wall, and X the cells beyond a clue that is already satisfied.
- Cross-check. After each fill, look at the crossing line - a new filled or empty cell there often forces the next move.
- Mark every empty. Whenever a line's clue is complete, X out the rest of that line so no run can creep into it.
- Loop back to the lines you skipped; each completed line makes its neighbours easier, so a board that felt stuck five moves ago usually has fresh forced cells once you look again.
Guessing never appears in that list, and in a properly built puzzle it never has to. If you feel cornered, you have almost certainly missed an X somewhere - re-walk the lines you thought were finished.
Common beginner mistakes
- Only filling, never X-ing. Marked empties shrink the search space as much as filled cells do. Track both kinds of certainty or the board will feel stuck when it is not.
- Ignoring clue order. A clue of 3 1 is not 1 3. The first number is always the leftmost (or topmost) run; reading them backwards quietly poisons the whole line.
- Forgetting the mandatory gap. Separate clue numbers always have at least one empty cell between them. That gap is free information when you are counting whether a line fits.
- Tunnel vision on one line. Nonograms are won at the crossings. If a row stalls, fill a column that crosses it and come back.
- Guessing to save time. One wrong fill can quietly break a dozen later cells. Slower logic is faster than untangling a contradiction.
Where to go next
The fastest way to make all of this automatic is to play on small grids until the overlap and edge moves feel like reflexes. Mochi Pixel keeps the boards gentle on purpose - it hands you exactly as many blocks as the picture needs and counts down how many are left, so you can never over-fill, and a finished picture lights up tile by tile. Start in the 3×3 Berry world, let the 6×6 Ocean and Galaxy boards stretch you, then turn to Endless for an unlimited supply. If you enjoy the "what is already forced?" feel of a nonogram, the pure-logic puzzles below scratch the same itch.