Shading Puzzles
Every puzzle here asks the same question in a different way: which squares are shaded, and which stay clear? Nothing is filled in by feel — each square is forced by the ones already settled.
What All Ten Have In Common
A shading puzzle gives you a grid and a set of constraints, and the answer is a pattern of filled and empty squares. What changes between the ten is what the constraints are about — runs of cells in a nonogram, duplicate numbers in hitori, region sizes in nurikabe, neighbouring mine counts in minesweeper.
The habit that carries all of them is the same: mark what is definitely empty, not just what is definitely filled. A cross is as much a deduction as a shaded square, and solvers who only shade go round in circles.
Why Connectivity Changes Everything
Three of these — hitori, nurikabe and heyawake — require the unshaded squares to stay joined as one group. That single rule reaches across the whole grid: a square in one corner can be settled by what shading it would do to the opposite corner.
It is also what makes them harder to build than to solve. A grid that satisfies every local rule can still be wrong because it cuts the board in two, so every puzzle here is checked for connectivity before it is shown.
Where To Start With Each One
Nonogram first: its clues are the most direct, and the overlap method is visible on a single line. Then binary puzzle, where the rules are three short sentences, and minesweeper, where every number is shown from the start. Hitori and nurikabe next, because they introduce connectivity. Shikaku, akari and dominosa each turn on one idea worth meeting on its own. Heyawake and star battle last — both need you to reason about regions rather than lines.
| Type | The clue is about | The rule people miss |
|---|---|---|
| Nonogram | Runs of shaded cells in a line | A sparse clue forces nothing — dense grids are easier |
| Hitori | Duplicate numbers in a row or column | Shaded squares may not touch, so a duplicate pair fixes its neighbours |
| Nurikabe | Island sizes | The sea can never form a 2×2 block |
| Heyawake | How many painted squares each room holds | No unpainted run may span three rooms |
| Star battle | One star per row, column and region | Stars may not touch diagonally either |
| Binary puzzle | Balance of 0s and 1s | No two rows may be identical — that is a real constraint, not a formality |
| Shikaku | A rectangle's own area | Every number is shown — nothing is stripped, so the puzzle is the boundaries, not the numbers |
| Akari | Bulbs touching a wall | A bulb lights its whole row and column, so one bulb can settle cells far from any wall |
| Dominosa | Nothing — the grid itself is the clue | A pair that only touches once anywhere on the grid has to be that domino |
| Minesweeper | How many mines touch each numbered square | Every number is shown from the start, so it is deduced and never guessed — unlike the game |
Printing A Shading Puzzle
These are the puzzles that print best, because a shaded square is a shaded square on paper as much as on screen — and a pencil beats a mouse for filling one in. Printing from any of the ten pages drops the navigation, the sixty-puzzle picker and the footer, keeps the grid and the clues, and leaves the explanation open so the working comes with it.
Worth knowing before you print: use the crosses. On paper there is no undo, and the solvers who get into trouble are the ones who shade without ever marking a square as definitely empty.
What Shading Puzzles Actually Train
The transferable skill here is elimination under a constraint — deciding what something cannot be, and acting on that rather than waiting for certainty. It is the same move whether the constraint is a run length, a duplicate number or a region size, which is why people who get comfortable with one of these ten pick up the others quickly.
What they do not train is arithmetic. Nothing on these pages needs more than counting, and the numbers are labels rather than sums.
| Type | Grid sizes here | Roughly how long |
|---|---|---|
| Nonogram | 5×5 to 20×20 | Two minutes small, half an hour at 20×20 |
| Binary puzzle | 6×6 to 12×12 | Five to fifteen minutes |
| Hitori | 5×5 to 8×8 | Five to twenty minutes |
| Nurikabe | 5×5 to 8×8 | Ten to twenty-five minutes |
| Star battle | 5×5 to 7×7 | Five to twenty minutes |
| Heyawake | 6×6 to 7×7 | Ten to thirty minutes |
| Shikaku | 5×5 to 9×9 | Five to twenty minutes |
| Akari | 6×6 to 9×9 | Five to twenty minutes |
| Dominosa | 4×5 to 7×8 | Ten to twenty-five minutes |
| Minesweeper | 6×6 to 12×12 | Three to twenty minutes |
Shading Puzzles Frequently Asked Questions
What is a shading puzzle?
A grid puzzle where the answer is a pattern of shaded and unshaded squares rather than numbers or letters. Clues tell you something about the pattern — how long the runs are, how big the regions are, how many squares a room holds — and you work backwards to the only shading that satisfies all of them.
Do I need to guess at any point?
No. Every grid on these pages is checked twice before it is shown: once that it has exactly one solution, and once that a solver using only human techniques can reach that solution without ever guessing. A grid failing either check is discarded and a different one generated.
Which shading puzzle is easiest to learn?
Nonogram. Its clues describe one line at a time, so you can see a whole deduction without looking at the rest of the grid. Binary puzzle is the next easiest because its rules fit in three sentences. Heyawake and star battle are the two that need you to think about regions.
Why do I need to mark empty squares?
Because a square you have ruled out is a deduction, and the next deduction usually depends on it. In a nonogram a run can only be placed once you know where it cannot go; in hitori a square is kept only once its neighbours are shaded. Solvers who shade but never cross tend to stall.
Are these the same as Nikoli puzzles?
Several of them were popularised by the Japanese puzzle magazine Nikoli, including hitori, nurikabe, heyawake, shikaku and akari. The mechanics are not owned by anyone and the puzzles here are generated rather than reprinted, but the names and rules are the standard ones you will find elsewhere.
Related Practice
Number logic puzzles ask for digits rather than shading but reward the same discipline of ruling things out. Loop puzzles apply it to lines instead of squares, and figure puzzles swap the grid for shapes.