How to Play Nonograms

What is a nonogram?

A nonogram (also called a picross, griddler, or hanjie) is a logic puzzle where you fill in cells on a grid to reveal a hidden picture. Each row and column has a sequence of numbers that tells you how many consecutive filled cells appear in that line — and in what order.

Nonograms were invented independently in Japan and the UK in the late 1980s. The name "picross" comes from Nintendo's "Picture Cross" series. Today they are one of the most popular logic puzzle types in the world, alongside sudoku and crosswords.

How to read the clues

Each row and column shows a list of numbers. These numbers represent runs of filled cells. For example:

• 3Fill exactly 3 consecutive cells.
• 2 1Fill 2 cells, then at least one gap, then 1 cell.
• 1 1 1Three separate filled cells, each separated by at least one empty gap.

The runs must appear in the order listed, left-to-right for row clues and top-to-bottom for column clues. There must be at least one empty cell between any two runs.

Step-by-step: how to solve a nonogram

1. 1
   Start with the longest clues

   Look for rows or columns where a single clue is almost as long as the grid. If your grid is 10 wide and a row clue is "8", the run of 8 must overlap somewhere in the middle — cells 3 through 8 are guaranteed to be filled no matter where the run starts.

2. 2
   Use the overlap technique

   Mentally slide each run to its leftmost and rightmost possible position. Any cell that is filled in both positions is definitely filled. Mark those cells straight away.

3. 3
   Mark empty cells too

   Confirmed empty cells are just as useful as filled ones. Use an X or dot to mark them — this prevents you from placing runs where they can't go.

4. 4
   Cross-reference rows and columns

   Every cell belongs to both a row and a column. When you fill or empty a cell, immediately check what that means for the crossing line's clue. This is how most deductions happen.

5. 5
   Repeat until solved

   Work through every row and column, applying what you know each time. As you fill in more cells, new deductions become possible. A correctly designed nonogram always has exactly one solution reachable by pure logic — no guessing needed.

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Beginner tips

• ✓Always mark empty cells with an X — a blank cell is ambiguous, an X is a definite decision.
• ✓If a row is fully solved (all runs satisfied), mark the remaining cells as empty.
• ✓Numbers that turn green have been satisfied — you can largely ignore those lines.
• ✓Don't guess. If you're stuck, there's always a logical deduction waiting — look at columns for rows you're stuck on, and vice versa.
• ✓Start with the largest grids' easiest rows. On a 10x10 grid, a clue of "9" or "10" can be filled almost immediately.