Nonogram rules
A nonogram is a picture hidden in a grid. Every row and every column has a clue: a few numbers that say how many cells in that line are shaded, and in what groups. Shade the right cells and the picture appears.
They are also called Japanese crosswords, griddlers, hanjie or paint by numbers. The rules are the same under every name, and there is no maths in them beyond counting.
The grid and the clues
The grid is square: 5×5, 10×10, 15×15 or 20×20 cells. The clues for the rows are written to the left of each row, and the clues for the columns above each column.
A clue lists the groups of shaded cells in that line, in order: from left to right for a row, from top to bottom for a column.
- "3 1" means a group of three shaded cells, then a group of one.
- Between two groups there is at least one blank cell. There may be more; the clue does not say how many.
- There may also be blank cells before the first group and after the last.
- "0" means the line has no shaded cells at all.
So a clue tells you how the shaded cells are grouped, but not where the groups are. Finding where is the puzzle. The row's clue and the column clues that cross it work together: a cell has to fit both at once.
Marking cells
A cell can be in one of three states:
- Shaded: you think it belongs to the picture. Click it, or tap it.
- Crossed out: you know it is blank. Right-click it, or switch the panel beside the grid from Shade to Cross out and tap. A cross is only a note for you. It does not count either way when the puzzle is checked, but it is the quickest way to remember what you have ruled out.
- Empty: not decided yet.
To take a mark off, press the cell again with the same tool: a shaded cell you click again goes back to empty, and so does a cross you right-click again.
Drag to mark several cells at once. Press on a cell and drag along its row or its column: every empty cell you pass gets the same mark. A drag that starts on a cell already carrying that mark rubs it out of the cells it passes instead, which is the fastest way to clear a mistake.
Undo (or Ctrl+Z, ⌘Z on a Mac) takes back the last stroke, and the one before that, as far back as you like.
Lines that are done
When a line on your sheet matches its clue, the clue is struck through in pencil. That only says your shaded cells in that line make the right groups. It does not mean they are in the right places: a row with the clue 2 matches whichever two neighbouring cells you shade. A struck-through clue is a reminder that the line needs nothing more, not a promise that it is right.
When it is solved
The puzzle is solved the moment the shaded cells are exactly the picture. Crosses do not matter: you do not have to cross out every blank cell, only shade every cell that belongs.
Nobody tells you when a cell is wrong. As on paper, a mistake shows up later, as a line that cannot be made to fit. That is the classic way to play, and it is what makes a solved nonogram yours.
Every puzzle has one answer
The puzzles here are dealt fresh every time, and each one is checked before you see it: it has exactly one answer, and you can reach it without guessing, working one row or one column at a time. If you are stuck, there is always a line with something left to find in it. The strategy guide shows how to find it.
A worked example, the smallest size. First the full rows: a clue of 5 in a row of five leaves no choice.
The four sizes
| Size | What it is like |
|---|---|
| 5×5 | A warm-up, a minute or two. Good for learning. |
| 10×10 | The classic size, five to ten minutes. |
| 15×15 | A proper puzzle: a quarter of an hour or more. |
| 20×20 | A long one, half an hour and up. On a phone, zoom in with two fingers. |
The clock starts with your first mark. If you leave in the middle, the puzzle is kept in your browser and comes back when you open the page again.
If you give up, Show the answer ends the puzzle and draws the picture, with any cell you shaded that should have been blank struck through in red.
Racing friends
Send the link to a table to up to three friends and you race each other on the same puzzle, two, three or four of you.
- You each solve it on your own sheet, at the same time. There are no turns.
- Whoever opened the table picks the size. Before the start, every friend who has sat down presses Ready, and whoever opened the table sees it and presses Start (at least one friend has to be seated). The race is dealt for everyone seated at that moment; anyone who arrives later watches. The clues appear for all of you at the same moment. Until then the grid has empty margins, so nobody gets a head start.
- Solve it first and you win. The race ends there for everyone, and everyone else loses.
- You see how far each of the others has got, as a share of their lines that match their clues. You never see which cells they have shaded, and they never see yours.
- Resign puts you out, and you have lost; the others race on, and whoever is left alone in the race wins. Someone who loses their connection has 60 seconds to come back; after that the others can race on without them, as if they had resigned.
- Anyone still racing can offer a draw. It is a draw only when everyone still racing agrees; declining it, or carrying on shading before agreeing, turns it down.
After a race, Play again deals a new puzzle of the same size for the same players straight away, everyone moving one seat round, and keeps the score. Whoever opened the table can press Change settings instead, to pick another size first, and someone new can sit down then. The score is kept then too.
Playing on your own
On your own there is no computer on the other side: the puzzle is the opponent. Pick a size and start marking. The panel shows the time and how many of the lines already match their clues.
Ready? Solve a nonogram, or read how to solve nonograms first. If you like working things out from numbers, try minesweeper too.