How to Play Picross — 5 Techniques From Easy to Expert
Picross (also called Nonograms or Hanjie) was developed by Tetsuya Nishio in Japan in the late 1980s. The rules: a grid where each row and column has numbers indicating filled-cell run-lengths. Use logical deduction to figure out which cells are filled. Here are the 5 techniques that take you from ‘I can’t even start’ to consistently solving Expert puzzles.
Reading the clues
Numbers on a row mean: ‘consecutive runs of filled cells, in order.’ Example: 3 2 means three filled cells, at least one empty, then two filled cells. The minimum length needed is 3 + 1 + 2 = 6 cells.
Same for columns. Together, row and column clues fully determine the puzzle (in a well-formed puzzle).
Technique 1: Edge solving
Look at any row where the run-lengths sum (with required gaps) to MORE than half the grid width. Then some cells in the middle MUST be filled — there’s no way to fit the runs without overlapping.
Example: a 10-cell row with clue ‘8’. The 8-cell run must include cells 1-8 OR cells 2-9 OR cells 3-10. The cells that appear in ALL three placements are 3, 4, 5, 6, 7, 8 — the middle 6 cells. Fill them.
Technique 2: Overlap method
For any run-length R in a row of width W where R > W/2, some cells will be filled regardless of placement. The minimum required cells in this overlap = R – (W – R) = 2R – W.
Apply to each clue independently. Combine the overlaps. You’ll typically fill 30-40% of the grid before doing any ‘real’ deduction.
Technique 3: X-ing impossible cells
Once you’ve placed some filled cells, look for cells that CAN’T be filled. Mark them with an X (crossed out).
Example: if you’ve established that the first filled cell in row 5 is at column 3, then column 1 and 2 of row 5 must be empty. Mark them with X.
Technique 4: Counting from edges
In a 10-wide row with clue ‘4 3’, the LATEST the first run could end is at column 5 (leaving room for 1 empty + 3 filled). The EARLIEST it could end is at column 4.
So column 4 is in the first run’s possible positions. Filled? Not certain. But the cell at column 5 must be the gap or the start of the next run.
This kind of forward-counting from edges narrows down each run’s possible positions.
Technique 5: Contradiction (advanced)
If you’re stuck and a cell could be filled OR empty, try one. Follow the deduction chain. If you reach a contradiction (some clue can’t be satisfied), the cell must be the other value.
This is called ‘fishing’ or ‘forcing chain’ in Picross. Use sparingly; most Easy and Medium puzzles solve without contradiction.
Practice
Play our Picross at 5×5 (Easy) until you can solve in 2 minutes. Then 10×10. Then 15×15. Each difficulty introduces new techniques.
