Crowns: The One-Per-Region Puzzle You'll Finish in Five Minutes 👑

The rules

A grid split into coloured regions. Place crowns so that:

• every row has exactly one crown,
• every column has exactly one crown,
• every colour region has exactly one crown, and
• no two crowns touch — not side by side, not diagonally.

How to actually solve one

The productive move is almost never "where does a crown go" — it's "where can a crown not go". Mark cells out aggressively.

Start with the small regions. A region that only occupies two rows must use one of them, which tells you something about the other rows before you've placed anything.

Then use the pigeonhole. If two regions together only touch two columns, those two regions consume both of those columns — so every other region can be marked out of them. This is the single highest-value pattern in the game, and it's the same argument as a naked pair in Sudoku wearing different clothes.

Then place. A region with only one unmarked cell left gets the crown, and placing it marks out its whole row, its whole column and all eight neighbours — which usually cascades.

The no-touching rule is the whole game

Without it, this is a mildly interesting placement puzzle. With it, every crown you place removes up to eight extra cells, and it's the diagonal exclusions that produce the long chains. When you're stuck, check the diagonals — that's where the missed deduction usually is.

About our version

99 levels growing from small grids to large ones with awkward region shapes. Tap once to mark a cell out, twice to place a crown. Unlimited undo, hints, and every board verified to have exactly one solution.

It runs in your browser, works offline once loaded, needs no account, and costs nothing.

Questions people actually ask

Is Crowns the same as the N-Queens problem?
It's a cousin. N-Queens forbids sharing a diagonal at any distance; Crowns only forbids touching diagonally, and adds the colour-region constraint. That swap is what turns it from a maths exercise into a puzzle you can solve by hand.

Can two crowns be diagonally adjacent?
No. Crowns may not touch at all, including corner to corner.

Is there always one solution?
Yes. Every level is generated and verified to have exactly one valid arrangement, so you never need to guess.

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