How to Play Nonograms

Basic Rules

Nonograms (also called Griddlers or Paint by Numbers) are logic puzzles where you fill in cells on a grid to reveal a hidden picture.

  1. Read the clues: Numbers on the left and top of the grid tell you which cells to fill in that row or column.
  2. Understand the numbers: Each number represents a group of consecutive filled cells. Multiple numbers mean multiple groups separated by at least one empty cell.
  3. Fill cells: Click to fill a cell black. The filled cells must match the clue pattern.
  4. Mark empty cells: Right-click to mark a cell with × to indicate it's definitely empty. This helps track your progress.
  5. Complete the puzzle: When all cells are correctly filled or marked, the hidden picture is revealed!

Understanding Clues

Single Number

A clue of [3] in a 5-cell row means exactly 3 consecutive cells are filled:

3→

Multiple Numbers

A clue of [2, 1] means a group of 2, at least one gap, then a group of 1:

2,1→××

Zero Clue

A clue of [0] means no cells are filled in that row/column:

0→×××××

Solving Strategies

1. Overlap Method

Look for rows/columns where the clue is large relative to the line length. The "overlap" of possible positions tells you which cells must be filled. For example, a clue of [7] in a 10-cell row means cells 4-7 must be filled no matter where the block starts.

2. Edge Logic

If you know where a block starts or ends, you can determine more cells. If the first cell must be filled for clue [3], then cells 1-3 are filled.

3. Full Lines

When the sum of clue numbers plus minimum gaps equals the line length, there's only one solution. For [3,2] in a 6-cell row: 3+2+1(gap)=6, so it must be ■■■×■■.

4. Cross-Reference

Always look at both row and column clues for each cell. Information from one direction often helps solve the other.

5. Mark Empty Cells

Use the × mark for cells you've determined are empty. This helps visualize remaining possibilities and prevents mistakes.

Controls

  • Left-click: Fill/unfill a cell
  • Right-click: Mark/unmark cell as empty (×)
  • Ctrl+Z / ⌘+Z: Undo last action
  • Ctrl+Shift+Z / ⌘+Shift+Z: Redo action