How to play nonograms
A nonogram hides a pixel picture behind number clues. Here are the rules and the core techniques that crack every board — no guessing required.
The rules
- The numbers beside a row (or above a column) list the runs of filled cells in that line, in order. "4 2" means: a block of 4, a gap, then a block of 2.
- Runs are separated by at least one empty cell — they never touch.
- A 0 means the line is completely empty.
- The board is complete when every row and column matches its clues.
Controls
- Fill tool paints cells; tap a filled cell to erase it.
- ✕ Mark tool notes cells you've proven empty. On desktop, right-click marks ✕ without switching tools.
- Drag across cells to paint a whole run in one stroke.
- Clues turn pale when their line is complete.
Solving strategies
- The overlap technique. Push a run as far left as possible, then as far right as possible. Any cells the two positions share are filled in every legal arrangement — fill them. A 7-clue in a 10-wide line always covers the middle 4 cells.
- Edge logic. Once a filled cell touches a wall (or an ✕), the run it belongs to is anchored — count it out and ✕ the cell after it.
- Split lines with ✕s. Every ✕ divides a line into independent segments. A segment too short for the next run can be ✕-ed entirely.
- Finish and close. When all of a line's runs are placed, ✕ every remaining cell — those ✕s are new anchors for the crossing lines.
- Alternate directions. Sweep rows, then columns, then rows again. Each pass feeds the next; our boards are generated so these passes alone always finish the job.
A worked example
Take a 10-wide row with the clue "6 2". The leftmost arrangement occupies cells 1–6 and 8–9; the rightmost occupies 2–7 and 9–10. Comparing the two: cells 2–6 are filled in both extremes of the six-run, and cell 9 in both extremes of the two-run — so six cells are certain before you look at a single column. Now the columns crossing those cells have anchored runs of their own, and the cascade begins.
Common mistakes
- Guessing. You never need to — if you're stuck, re-scan for overlaps and for lines that are nearly complete. There is always a next logical move.
- Forgetting the gap rule. "2 2" is not four in a row — runs must be separated by at least one empty cell.
- Skipping the ✕s. Marking proven-empty cells is what turns one deduction into a chain. Fill-only play stalls quickly on 10×10 and up.
- Reading clues out of order. The numbers are strictly left-to-right (top-to-bottom for columns) — the first clue is the first run you meet.
Frequently asked questions
- What's the difference between nonogram, Picross and picture cross?
- Different names for the same public-domain puzzle type. "Picross" is Nintendo's series; "griddlers" and "hanjie" are other common names.
- Do I ever need to guess?
- No — every board here is generated to be solvable line-by-line with pure logic, and each has exactly one solution.
- Is there a daily puzzle?
- Yes — a shared 10×10 Daily Challenge with streaks, plus unlimited random boards in 5×5, 10×10 and 15×15. Free, no login.