Nonogram (also called Picross or Griddlers) is a picture logic puzzle. Use the numbers next to each row and column to fill in cells, and a pixel picture appears at the end.

There is a new picture every day, checked so it can be solved by logic, without guessing.

How to play

1. The numbers show the lengths of the filled runs in that row or column, in order.
2. There must be at least one empty cell between two runs.
3. Tap to fill a cell and mark cells you know are empty with an X.
4. If you get stuck you can use up to three hints a day.

Tips

• Start with the big numbers: the middle of a long run is often certain.
• If a row's clue is 0, or the row is complete, mark the rest with X.
• Switch between rows and columns: what you learn in one helps the other.

Strategy

• The strongest technique is overlap. Slide a run as far left as it can go, then as far right: any cell covered in both positions must be filled. In rows with several runs you can do the same for each run separately.
• Watch the edges. If the first cell of a row is filled, the first run starts there, so you can fill its full length and cap it with an X. The thicker lines that split the grid into blocks of five make counting cells much faster.
• Crosses matter as much as fills. Every cell you know is empty shortens the space available to the runs in the crossing lines, and that is often where the next certain cell comes from.
• Clues for finished rows and columns fade out and are struck through. Once every clue in a line is done, the remaining cells must be empty, so cross them all out.

A worked example

Take an invented 10×10 example. One row has the clue 3 6. The two runs plus the mandatory gap between them come to 3 + 1 + 6 = 10 cells, exactly the width of the row: the first three cells are filled, the fourth is empty and the last six are filled. Rows that fill completely like this are worth finding first.

Another row has the clue 8. Pushed left the run covers cells 1-8, pushed right it covers 3-10, so cells 3-8 are certain: six cells from a single number. Those cells feed the columns too. If a column's clue is 1 and its cell in this row is now filled, every other cell in that column gets an X.

History of the game

Nonograms were invented independently in Japan in 1987 by two people: graphic artist Non Ishida, who came up with grid pictures after winning a competition with an image made of lit windows, and puzzle maker Tetsuya Nishio. The name nonogram blends Ishida's first name with the word diagram.

British newspapers brought the puzzles to Europe in the early 1990s, and they have also been sold as Griddlers and Paint by Numbers. Nintendo made them famous among gamers with Picross in 1995, a name many players still use today.

Frequently asked questions

What is the reward?

Once solved, the day's pixel picture is revealed and you can share it with friends.

How big is the grid?

Grid size can vary per puzzle; it is usually around 10×10.

What does a hint do?

It scans the grid row by row from the top left, finds the first wrong cell and fixes it: it fills a missing cell or crosses out one you filled by mistake. You get three hints a day, and the number you used appears in your result.

Can I fill several cells at once?

Yes, press and drag across the cells with your finger or mouse. On a computer the right mouse button always places an X, whichever tool is selected.