Nonogram (Picross, Griddlers)
Reveal hidden pictures through logic
Nonograms (also called Picross, Griddlers, Hanjie, or picture cross puzzles) are picture logic puzzles where you fill cells based on number clues to reveal a hidden image. Invented in Japan in the late 1980s, they became world famous through Nintendo's Picross series. Each puzzle has a unique solution that can be found through pure logic, no guessing required. This guide covers the rules, how to start a nonogram, and the solving techniques that take you from beginner to expert.
Rules
You're given a grid of empty cells. Numbers along the top and left edges tell you which cells to fill in each column and row.
Each number represents a group of consecutive filled cells. Multiple numbers mean multiple groups, separated by at least one empty cell. For example, '3 2' means a group of 3 filled cells, then a gap, then 2 filled cells.
Click to fill a cell. Right-click or use the X tool to mark cells you know are empty. Marking empty cells is just as important as filling cells.
Fill all the correct cells to reveal the hidden picture. The puzzle is complete when all clues are satisfied.
Strategies & Tips
Start with Large Clues
Look for rows or columns where clues take up most of the space. If a row is 10 cells wide and the clue is '8', you know the middle 6 cells must be filled no matter where the group starts.
Use Overlap Logic
Calculate where groups must overlap. If a clue of '7' can start at position 1 or 2 in a 10-cell row, positions 2-7 are definitely filled (the overlap of both possibilities).
Mark Empty Cells
When you complete a group, mark the cells on either side as empty. This prevents accidentally extending the group and helps identify where other groups can go.
Cross-Reference
Work both rows and columns together. Filling cells in a row gives you information about columns, and vice versa. Alternate between them to make steady progress.
Anchor from the Edges
When a filled cell sits on or near a border, count outward from it. If the first clue in a row is '4' and the first cell is filled, the next three cells must be filled too, and the fifth cell must be empty.
Count from Both Ends
Try placing the clue groups as far left as possible, then as far right as possible. Any cell that is filled in both extreme placements must be filled in the real solution. This is the core technique behind most deductions.
Finish Rows to Unlock Columns
A completed row lets you mark its remaining cells empty, which often turns an unsolvable column into an easy one. Momentum builds: each solved line feeds the lines that cross it.
Never Guess
Every nonogram has a logical solution. If you're stuck, look for another row or column with more information. A wrong guess can cascade into many errors.