- Grid: 20×20
- Filled cells (solution): 221 / 400
- Fill density: 55%
- Longest row hint run: 10
- Longest column hint run: 9
- Average hint groups: rows 5.3 • cols 5.5
Hard Nonograms have longer deduction chains and fewer immediate certainties. With a 20×20 grid and ~55% filled density, work systematically and revisit lines after each confirmed fill.
- Work systematically: rotate between rows and columns after every confirmed placement.
- Track partial run completion: once a run is satisfied, mark remaining cells in that segment as blank.
- Avoid random guessing — use contradictions: if a hypothetical placement forces impossible hints, eliminate it.
- Try today’s other difficulties: Easy · Medium
- Previous days (Hard): Tue, Dec 9 · Mon, Dec 8 · Sun, Dec 7 · Sat, Dec 6 · Fri, Dec 5 · Thu, Dec 4 · Wed, Dec 3
What do the numbers mean?
Each number shows a group of filled cells in that row or column. Multiple numbers mean multiple groups, separated by at least one blank cell.
Is X-mode required?
It’s optional, but it helps a lot. Marking definite blanks prevents accidental fills and makes deductions easier.
Do I need to guess?
No. These puzzles are designed to be solved logically using overlaps, spacing, and elimination.
💡 How to play: Use the numbers above and to the left of the grid to decide which cells to fill. Each number shows how many squares are filled consecutively in that row or column. Use X-mode (Ctrl + left-click or just right-click) to mark cells that must stay empty — it helps eliminate options and avoid mistakes.