15×15 · Hard
Hard Nonogram puzzle
A larger grid for experienced solvers who enjoy a longer chain of deductions.
A deeper picture-logic challenge
Hard puzzles use a 15×15 grid with longer clue sequences and more interactions between rows and columns. The solution never requires guessing, but progress may depend on combining several small deductions.
Playing 15×15 on a phone
The squares stay large enough to tap; the board pans instead of shrinking. Use the Move tool, or drag from the clue gutter, so a pan does not mark a cell by accident. Start with the fullest lines: add the clue lengths, then add one empty square between each pair of groups. If that total is close to 15, the overlapping squares are filled whichever way the groups slide — mark those first, then pan to the crossing lines they unlock.
Controls that support careful play
Drag to mark a run of cells, use crosses to protect known gaps, and undo the latest action when needed. On narrow screens the board scrolls in a controlled area without changing the puzzle.
Common questions
- How long does a 15×15 nonogram take?
- Typically fifteen to forty minutes. The grid rewards patience: most of the time goes into short deductions that each unlock one more line.
- Does a 15×15 grid fit on a phone?
- The squares stay large enough to tap, so on a narrow screen the board pans instead of shrinking. Use the Move tool or drag the number gutter; the row and column clues stay pinned while you pan.
- Is guessing ever needed on hard puzzles?
- No. Hard puzzles are longer, not ambiguous — every one is verified to have a single solution reachable by deduction.
- What is the fastest way to make progress?
- Work the most constrained lines first: any line whose clues plus their mandatory gaps nearly fill its length has squares that must be filled whichever way the groups slide.