Queens puzzle maker: you paint, the dodo checks

How to make a Queens puzzle

1. Pick the size with the − and + buttons, from 4 × 4 to 16 × 16. You need as many gardens as rows: a 9 × 9 grid has nine colours.
2. Paint the gardens. Pick a colour and slide your finger across the squares. The paint bucket fills a whole same-colour area at once, the eraser clears.
3. Or start from a generated grid: “Generate a grid” draws one at the chosen difficulty, which you can then reshape as you like.
4. Read the verdict under the grid. It changes with every brushstroke.
5. Send it. Give it a name if you like, try it yourself, then “Send to a friend”.

What makes a good grid

A good Queens puzzle has exactly one solution, and you must be able to reach it by deduction, without ever trying a square just to see. The maker checks both after every change: it counts the solutions (it stops at two, one too many is enough to decide), then replays the grid with the six deductions of the Dodoku game, the ones that validate every one of its levels.

• Small gardens get things started. A garden of one or two squares gives the player a first foothold. Without any, the grid starts in a fog.
• A garden lying along one row locks it. Its dodo has to be there, so the rest of the row is out: the most satisfying deduction to spot.
• Beware of symmetry. If your grid mirrors itself, the reflection of one solution is often a second solution.
• Huge gardens water everything down. A garden that touches every row constrains almost nothing: cut it or tighten it.

The two buttons that fix things

“Make it unique” shows up when your grid has more than one solution. The maker keeps one of them, then hands a square where a dodo of the other solution sleeps to the neighbouring garden: the intruder loses its spot, yours loses nothing. It repeats until only one is left, without ever cutting a garden in two.

“Make it guess-free” shows up when the solution is unique but the deductions stall on the way. The maker tries small border tweaks, keeps the ones that move the deduction forward, and stops as soon as the grid solves from start to finish. Either way, the squares it touched are circled in red, and “Undo” puts them back.

Sharing your grid with a friend

“Send to a friend” opens your phone’s share sheet, or copies the link on a computer. The grid and its name are kept on our server for a year, under an eight-character id: that is what keeps the link short, and what lets the game tell you when your friend has solved it. Your friend opens it in the Dodoku game itself, in their browser: tap to put a dodo to bed, slide to cross out, and the same hints as in the levels.

The “Image” button makes a PNG of the empty grid, with its name: to print it, or to post it.

Up to 16 × 16, and no further

LinkedIn’s Queens usually stops at 11 × 11. Here you can go up to 16 × 16: sixteen gardens, two hundred and fifty-six squares, and a verdict that keeps up with your brush. Beyond that, checking that a grid solves without guessing takes too long to stay live. Sixteen colours can’t all be told apart at a glance: the “Letters” button puts a letter in every garden, and it shows on the image too.

To solve a grid rather than invent one, the Queens solver reads a screenshot and gives one hint at a time. The rules and the six deductions are explained in the Queens puzzle guide.

Frequently asked questions