數織

Nonogram: rules and solving techniques

Use row and column clues to reveal a hidden pixel picture. This guide reflects the controls and win conditions in the current browser build. It is reviewed by the PocketJoy game-testing team and maintained by Long-Term New Media Limited.

Puzzle rules

Every row and column carries a sequence of numbers along its edge, giving the lengths of the runs of filled cells in that line, in order. For example, 3 1 means a run of three filled cells, at least one gap, then a single filled cell, while 1 3 means one then three — the order cannot be reversed. Your task is to deduce the unique solution from all the clues, revealing a hidden picture. Tap to fill a cell, and long-press or right-click to mark it with an × meaning definitely empty; marking is as important as filling, because known empty cells sharply narrow the possibilities in the crossing lines. Board sizes are selectable with a fastest time stored for each on your device, and a clear-board button lets you restart your reasoning without changing puzzle.

Reasoning and solving techniques

Start with the lines whose clue numbers add up to the most. Sum the numbers and add the mandatory gaps between them — n runs need at least n-1 gaps — and if the total equals the width of the board, that line is fully determined and can be filled straight away. Even when it is not, use the overlap method, which is the central technique of the genre: place the clues once packed to the far left and once packed to the far right, and any cell filled in both arrangements is certainly filled. In a row of width ten with a single clue of 7, the left packing occupies cells 1 to 7 and the right packing cells 4 to 10, so cells 4 to 7 must be filled. The method is most powerful for long clues, since the closer a clue is to the line width, the larger the overlap. After a pass, alternate between rows and columns: on completing a line, immediately re-examine the lines it crosses, because a newly placed cell or × frequently makes one of them solvable at once. A more advanced technique is edge reasoning: if the first cell of a line is known to be filled, the first run must begin there and everything after it follows.

Easy mistakes to make

The most common mistake is guessing on instinct. A nonogram has exactly one solution, so a single wrong cell produces a contradiction somewhere later, often long after the fact, and unwinding it is expensive — you cannot tell which step went wrong and usually have to clear and start again. The second is filling cells without ever using the × mark. Discarding the information about empty cells makes many otherwise available deductions impossible: knowing a cell is empty splits that line's clues into two independent intervals, which is an extremely strong constraint. The third is reasoning in one direction only, working through every row before looking at any column. The correct habit is to check the crossing lines the moment a row is finished, so information propagates immediately and forms chains. The fourth is persisting on too large a board; difficulty grows quickly with size, and if a big grid has you stuck, dropping a size to practise overlap and edge reasoning makes returning to it far smoother.

Who will enjoy it

Suited to patient players who enjoy logical deduction. It belongs to the same family as sudoku but adds the visual payoff of a picture appearing when you finish, which makes the final moment genuinely rewarding — you have not merely completed a table but drawn something. The puzzle was invented independently around 1987 by Tetsuya Nishio in Japan and Non Ishida in Britain, with Ishida winning a design competition for a picture formed by lighting windows in a Tokyo building, which is where the English name nonogram comes from. It spread worldwide through the Sunday Telegraph in the 1990s and became an established video game genre after Nintendo's Mario's Picross. There is no time pressure and you can pause whenever you like. Small grids are good for learning, while a large one can take a considerable session.

Helper features

Board size is selectable with a fastest time stored for each, and they never overwrite one another. The run panel shows the timer and how many cells you have filled, a figure that gives a rough sense of progress and is particularly useful on large grids. Two marking modes are provided with an explicit switch between them: fill for confirmed cells and × for confirmed blanks. In a nonogram the second matters as much as the first, because a known empty cell splits a line's clues and often constrains more strongly than a filled one does, and presenting it as an equal first-class function rather than a secondary option reflects the nature of the puzzle. The clue numbers along every row and column are fully visible without scrolling, which removes a constant distraction on larger boards. The clear-board button lets you restart your reasoning without moving to a new puzzle — important, because a wrong deduction in a nonogram often means starting the grid again while the puzzle itself remains worth another attempt. Completion shows your time with an option to generate a fresh puzzle.

Controls and saved progress

On desktop, left-click to fill and right-click to mark ×, or switch mode first and tap; on a phone, tap to fill and long-press to mark ×. Both marking modes are fully available on both platforms, so nothing is lost for want of a right button. A mistaken cell returns to blank with another tap, with no penalty and no time forfeited, so probing costs nothing — and since nonogram reasoning frequently involves revision, that zero-cost toggling matters. A fastest time per size is stored in the browser's local storage on your own device, with no account needed and nothing uploaded to any server; records do not travel to another device, and clearing browser data removes them. The language button switches between Traditional Chinese and English instantly, updating every panel label and prompt. Once the page has loaded, the game itself plays offline.

Solving FAQ

The overlap method and its relatives are covered in Nonogram Techniques: Overlaps and Line Switching.

Reviewed by the PocketJoy game-testing team · Operated by Long-Term New Media Limited · hklongtermad@gmail.com