How to Play Nonogram
Read the Clues
Each number on the left of a row (or above a column) tells you how many consecutive filled cells appear in that line. Multiple numbers mean multiple separate groups — in order — each separated by at least one empty cell. Start with the rows or columns that have the largest numbers, since they constrain the grid most tightly.
Fill and Mark Cells
Left-click (or tap on mobile) to fill a cell black. Right-click (or long-press on mobile) to mark a cell with an X, meaning you are certain it is empty. Using X markers is important — they prevent accidental fills and visually clean up the grid. Click and drag to fill or mark multiple cells in a single stroke.
Use Hints and Check Your Work
Stuck? Press the Hint button to reveal one logically guaranteed cell — it uses the overlap method to find a cell that must be filled regardless of where the run falls. Press Check to highlight any errors in red without penalizing your mistake count. Use Undo to revert any accidental fills.
Complete the Picture
The puzzle is solved when every filled cell in the solution matches your grid exactly — you do not need to mark every empty cell. When complete, the puzzle is highlighted and your time, mistakes, and hints are displayed. Then choose another puzzle from the selector to keep playing!
Frequently Asked Questions
What is a nonogram and how is it different from sudoku?
A nonogram (also called Picross, Griddlers, or Hanjie) is a picture logic puzzle where you fill cells in a grid based on number clues for each row and column. Like sudoku, the solution is found through pure logical deduction — no guessing required. Unlike sudoku, nonograms reveal a pixel-art image when solved, blending logic with creative reward. Sudoku uses digits 1–9 with constraint rules; nonograms use binary filled/empty states with group-size constraints. Nonograms also scale more naturally in visual difficulty: a 5x5 beginner grid and a 25x25 expert grid look and feel completely different, while sudoku difficulty depends on clue placement rather than grid size.
Do I ever need to guess in a nonogram puzzle?
A legitimate, well-designed nonogram never requires guessing. Every cell can be determined through logical deduction alone. The core technique — the Overlap Method — identifies cells that must be filled because every possible placement of a run covers them. Other techniques like Edge Logic and Completed Line Detection fill in additional certainties. If you find yourself guessing, it likely means you have missed a logical deduction elsewhere in the grid. The Hint button in this game always reveals a logically guaranteed cell — it will never point to a cell that requires guessing, because such cells do not exist in a properly constructed puzzle.
What is the Overlap Method?
The Overlap Method (also called Simple Boxes) is the most important solving technique in nonogram puzzles. For a run of length n in a line of length L, you find the leftmost possible starting position and the rightmost possible starting position. Any cell that appears in both the leftmost and rightmost placement must be filled regardless of where the run actually sits. Mathematically, cells from position (L - n) to position (n - 1) from the start of the available segment are guaranteed fills. For example, a run of 7 in a 10-cell row can start at cell 1 or cell 4 at the latest — so cells 4 through 7 are always filled. The longer the run relative to the available space, the more guaranteed cells you find.
What does the X marker mean and when should I use it?
The X marker (right-click on desktop, long-press on mobile) marks a cell as confirmed empty. Unlike leaving a cell blank (unknown), an X marker means you have logically determined that cell cannot be filled. Using X markers is highly recommended because they prevent accidental fills — if you know certain cells in a row must be empty to satisfy the column clues, marking them prevents confusion later. X markers also help visualize progress: a row filled with some black cells and some X markers looks much cleaner than a row with some fills and many unknowns. The X is purely a player note — the win condition only checks that filled cells match the solution. You do not need to mark every empty cell to win.
How does the Hint button work?
The Hint button in this game uses the Overlap Method to find a cell that is logically guaranteed to be filled. It scans all rows and columns looking for any currently unknown cell that must be filled based on the constraints of that line's clue and available space. When it finds such a cell, it fills it and increments the hints counter. The hint will never reveal a cell that would require guessing — it only reveals cells that are provably correct at the current game state. If no guaranteed cell exists (very rare in well-constructed puzzles), the button shows a message saying no hint is available. Using hints does not count as a mistake, but the number of hints used is tracked for scoring purposes.
Are nonograms good for the brain?
Yes — nonograms provide meaningful cognitive exercise. They require working memory to track multiple constraints simultaneously across rows and columns. They strengthen logical reasoning as you apply deduction techniques iteratively. They develop pattern recognition as you learn to spot constrained lines at a glance. Studies of puzzle-solving activities suggest that regular engagement with logic puzzles like nonograms, sudoku, and crosswords is associated with sharper reasoning skills and may contribute to maintaining cognitive health over time. Nonograms specifically add a visual-spatial component absent from purely number-based puzzles, since you are mentally composing a pixel image. They are also excellent for focus and mindfulness — the absorbing constraint-solving process is a natural attention anchor.