Nonograms — also called Picross, Griddlers or Hanjie — hide a picture inside a grid, and you reveal it using only the number clues along each row and column. They look cryptic at first, but they run on a handful of logical moves you can learn in one sitting. No artistic skill required; it's pure deduction.
Reading the Clues
Each row and column has a list of numbers. The numbers are the lengths of the filled runs, in order, with at least one empty cell between them. A clue of “4 2” on a row means a block of four filled cells, then a gap, then a block of two, in that order. Your task is to work out exactly where those blocks sit using the clues from the crossing direction.
Start Where the Numbers Are Biggest
The easiest entry point is any line whose clues nearly fill it. In a ten-cell row, a clue of “10” fills every cell; a clue of “8” guarantees the middle six are filled no matter how the block slides. This “overlap” technique — marking the cells that are filled in every possible position of a block — is the single most useful move in the whole puzzle, and big clues give you the most overlap.
Mark Empties as Hard as You Mark Fills
Beginners only fill cells; good solvers also mark known-empty cells, usually with a small X or a dot. Empties are just as informative as fills, because they wall off where a block can and can't go. Whenever you complete a row's clues, X out every remaining cell in it; those X's then constrain the crossing columns and crack them open. Treating empties as second-class is the most common reason a nonogram stalls.
Work the Crossings
The puzzle is solved by bouncing between rows and columns. A cell you fill from a row clue becomes a fixed fact for its column, and vice versa. Solve what a single line forces, then look at the crossing lines that line just changed, then back again. Distinctive lines — nearly full, nearly empty, or with one big number — are always your way back in when progress slows.
Never Guess
A proper nonogram has exactly one solution and never needs a guess. If you're stuck, you've missed an overlap or forgotten to mark some empties — scan for the line with the most constraint and work it again. Guessing risks corrupting the grid in ways that surface ten moves later as a contradiction you can't locate.
Bigger Grids and Colour Nonograms
The same logic scales to large grids and to colour nonograms, which add just one rule: runs of different colours need a gap between them only when they're the same colour, so two differently-coloured blocks can sit flush against each other. On big puzzles, don't try to hold the whole grid in your head — solve it region by region, leaning on whichever lines are most constrained, exactly as you would on a small one. The numbers may be longer, but every move is still one of the basics: find the overlap, mark the empties, and read across the crossings.
The Takeaway
Read the clues as ordered runs, start with the biggest numbers for guaranteed overlap, mark empties as diligently as fills, and bounce between crossing lines until the picture appears. It's a quiet, absorbing kind of logic — and the moment the hidden image resolves is genuinely satisfying.