Learn These 7 Rules First

Every nonogram solver — from casual hobbyist to speed-solving expert — relies on the same core principles. These 7 rules will take you from staring at a blank grid to confidently solving puzzles.

Rule 1: Start With the Biggest Clues

Look at every row and column. Find the ones with the largest numbers relative to the grid size. In a 10-cell row, a clue of 8 is far more useful than a clue of 2.

Why? Larger clues have fewer possible positions, which means more cells can be determined immediately.

Example: A clue of 7 in a 10-cell row. The block could start at position 1, 2, 3, or 4. Cells 4 through 7 are filled in every case — that’s 4 confirmed cells right away.

Rule 2: Use the Overlap Method

This is the single most important technique in nonograms. For any clue, imagine sliding the block as far left as possible, then as far right as possible. The cells where both positions overlap must be filled.

Formula: For a single block of size N in a row of length L, the overlap is 2N − L cells (when positive).

A clue of 6 in a 10-cell row: 2(6) − 10 = 2 cells of overlap, centered in the row. Those 2 cells are guaranteed filled.

Rule 3: Mark Empty Cells With X

This is the rule beginners most often skip — and it costs them. When you know a cell is definitely empty, mark it with an X.

When to mark X:

A row or column with clue 0 — every cell is empty
Cells on either side of a completed block
Cells that would make a block too long if filled

Marking Xs shrinks the problem. Once a cell is marked empty, every intersecting row and column gets new information to work with.

Rule 4: Count the Minimum Space

Every set of clues needs a minimum amount of space. Add up all the block sizes plus one gap between each pair of blocks.

Clue “3 2 1”: Minimum space = 3 + 1 + 2 + 1 + 1 = 8 cells

If the row is exactly 8 cells long, there’s only one possible arrangement. If the row is 10 cells long, you have 2 cells of slack — and the overlap method tells you which cells are still certain.

Rule 5: Work the Intersections

After making progress on a row, immediately check the columns that cross through your new filled or empty cells — and vice versa.

Example: You determine that row 3, cell 5 is filled. Now look at column 5. That new filled cell might complete a block, reveal a gap, or trigger another overlap calculation.

The best solvers develop a habit: fill a cell, check the cross. Mark an X, check the cross. This cascade of deductions is how puzzles unravel.

Rule 6: Use Edge Logic

When a clue starts with a number and the first cell of that row is already filled, the block must begin at the edge.

Example: Clue is 3 1 and cell 1 is already filled. The block of 3 must start at cell 1, filling cells 1-3. Cell 4 must be empty (gap before the next block).

The same logic works at the right edge. If the last cell is filled and the last clue number matches, that block is pinned to the edge.

Rule 7: Never Guess

This is non-negotiable. A properly designed nonogram can always be solved through logic alone. If you feel stuck, you haven’t found the next deduction yet — it’s there, you just need to look harder.

Common places to find hidden progress:

Rows where existing filled cells limit block positions
Columns where X marks eliminate possibilities
Lines that are almost complete — count remaining cells vs remaining blocks

Putting It All Together

Here’s a typical solving sequence on a 10×10 grid:

Scan for full rows: Any row where clues sum to the row length (including gaps) — fill it completely
Scan for zero rows: Clue of 0 — mark every cell X
Apply overlaps: Process the 3-4 rows/columns with the largest clues
Work intersections: Each new cell triggers checks on the crossing line
Use edge logic: Look for filled cells touching grid edges
Repeat: Keep cycling through rows and columns until the puzzle is complete

With practice, these steps become automatic. A 5×5 puzzle might take a minute at first, then 15 seconds once the patterns are internalized.

Practice Makes Pattern Recognition

The fastest way to build these skills is to solve many small puzzles. noguelike.com starts you with 5×5 nonograms in a roguelike dungeon setting — each puzzle you solve defeats a monster, so there’s real motivation to keep practicing. As you clear floors, the puzzles grow to 7×7 and beyond, naturally scaling the difficulty as your skills improve.

Start with Rule 1 and Rule 2. Those two alone will get you through most beginner puzzles. Add the rest as you encounter situations where they apply, and soon you’ll be solving grids that once looked impossible.