Nonogram

How to play

A nonogram (also called Picross, or a griddler) is a grid where every cell is either filled in or left empty, and the two together spell out a pattern — traditionally a picture, though the puzzle here is a pattern generated fresh each time rather than hand-drawn art. The numbers beside each row and column tell you the length of every unbroken run of filled cells in that line, in order — a clue of "3 1" means a run of three filled cells, at least one empty cell, then a run of one, somewhere along that line. Tap a cell to fill it in; tap again to mark it with an X (useful for cells you've worked out must be empty), and again to clear it. The puzzle is solved once your filled cells match every clue exactly.

Reading the clues

Start with the lines that give away the most. A clue with one number close to the full length of its line leaves very little room for that run to move — a clue of "8" in a ten-cell line, for instance, can only start in one of three places, and the middle six cells are filled in every one of them, so you can mark those with certainty before you've placed anything else.

Cross-reference rows against columns as you go. A cell you've determined must be filled in from its row's clue often tells you something new about that cell's column too, and working back and forth between the two is most of what solving a nonogram actually is.

Turn on "Highlight mistakes" below the board if you'd like the game to mark a filled cell in red the moment it doesn't belong — useful while you're still learning to read the clues, and easy to turn back off once you'd rather work it out yourself.