How to play

The numbers beside each row and above each column tell you the lengths of the filled runs in that line, in order, with at least one blank square between them. A row clued 4 2 holds a block of four filled squares, then a gap, then a block of two — somewhere. Your job is to work out where. Fill in the squares you have proved, cross out the ones you have ruled out, and a picture comes up out of the grid.

Left-click and drag to fill; right-click and drag to cross out. Clicking a square that is already filled clears it again. Every puzzle here can be finished by looking at one line at a time — you never have to guess.

Controls

• Left-click / drag — fill squares (drag locks to a row or column)
• Right-click / drag — cross out squares you have ruled out
• On a touch screen: drag to paint with the mode chosen in the toolbar, and pinch with two fingers to zoom into a large board
• ↑ ↓ ← → — move the cursor
• Space or F — fill the square under the cursor
• X or Delete — cross out the square under the cursor
• Z or U — undo
• H — use a hint (3 per puzzle)
• R — restart the puzzle

Strategy tips

• Start with the overlap. Push a line's blocks as far left as they go, then as far right; any square covered both times is filled no matter what. In a 10-wide row, a clue of 8 already gives you six squares for free.
• Cross out relentlessly. Crosses are not decoration — they are the constraints that make the next deduction visible. A line whose blocks are all placed can have every remaining square crossed at once.
• Work the edges. A filled square touching the border pins the first block exactly, and one filled square next to a cross does the same in the middle of a line.
• Follow the crossings. After finishing a row, check the columns it just changed — the information you gain almost always pays off at right angles.
• Never guess. Every puzzle in this collection was verified to fall to line-by-line logic alone. If you are stuck, there is a deduction on the board you have not spotted yet.

About Nonograms

Nonograms — also sold as Picross, Griddlers, Hanjie, or Paint by Numbers — were invented independently in 1987 by two Japanese puzzle-makers, Non Ishida and Tetsuya Nishio. They reached British newspapers a few years later and have been a staple of puzzle magazines and handheld games ever since.

This edition ships 750 puzzles: 300 at 10×10, 250 at 15×15, and 200 at 20×20. Each picture is generated, clued, and then handed to a solver that only knows how to reason about a single row or column at a time. If that solver cannot finish the grid, the puzzle is thrown away — so everything you play here has exactly one solution and needs no trial and error. Within each size, puzzles are ordered by how much work the solver had to do, so #1 is the gentlest.