Nonogram Game and Solver: Play Nonograms Online, Free

How to play nonograms: the rules

1. Each row and each column has a clue, a list of numbers.
2. The numbers are the lengths of the line's runs of filled cells, in order.
3. Two runs have at least one empty cell between them.
4. Fill the cells so every line matches its clue: the picture is the answer.

Nonograms 5×5, 10×10, 15×15 and 20×20

Every picture here is new, has one solution, and is solved by logic alone. The size sets how long it takes:

• 5×5a first nonogram: a few lines and the picture is there
• 10×10the classic size; the overlap and the edges carry most of it
• 15×15longer clues, where crosses matter as much as fills
• 20×20the big one: line after line, row and column in turn

How the nonogram solver works

It checks your clues first: each line's blocks fit in it, and the rows fill as many cells as the columns. Then it works the way a person does: for one line at a time, it finds every way the clue's blocks can lie with the cells known so far, and marks the cells all of them agree on. When no line gives anything more, it tries a cell and follows where that leads. It also says when the clues allow no picture, or more than one.

Where nonograms come from

In 1987 Non Ishida, a graphics editor in Tokyo, won a competition with pictures made of the lit windows of skyscrapers, and turned the idea into grid puzzles; Tetsuya Nishio, a puzzle maker, came to the same puzzle on his own at about the same time. In 1990 James Dalgety in Britain named them nonograms, after Non Ishida, and The Sunday Telegraph began printing them every week.