Crowns

Crowns is the queens puzzle, the one where nothing may share a line and nothing may touch. A seven by seven board, for instance, is painted into seven coloured regions and wants exactly one crown in every row, every column and every region, with no two crowns ever touching, diagonals included. Every board has exactly one solution, everyone gets the same one, and it flips at midnight UTC. The boards also grow through the week: the rules panel says Monday is the smallest and Sunday the biggest.

1. Tap a cell to cycle it through three states: empty, then a cross for a square you have ruled out, then a crown.
2. Place one crown in each row, each column and each coloured region.
3. Keep crowns off each other's diagonals as well as their rows and columns.
4. Lean on the controls under the board: Undo steps back, Hint unsticks you, Clear board starts the whole thing again. The counter beside the clock shows crowns placed against the number the board needs.

The n-queens problem is a piece of combinatorics that turns into a genuinely good puzzle once you add coloured regions, because regions and lines constrain each other in ways the eye can follow. Crowns gets the small things right: a three-state tap so ruling squares out is as quick as placing crowns, illegal crowns going red the instant they land, a guaranteed unique solution so guessing is never the answer, and boards that grow across the week so the daily is not the same size forever.

Immediate, and red. A crown that breaks a rule turns red where it stands, so the board tells you at the moment of placement rather than waiting for a submission. That one detail sets how the game is played: since a bad crown costs nothing but the sight of it, the cross mark becomes the real thinking tool and the crown becomes a commitment. A clock runs at the top from the first second and the crown counter tracks your progress toward the board's target.

Daily board

One board a day, identical for everyone, flipping at UTC midnight. The rules panel states that every puzzle has exactly one solution.

Archive

A dated archive link sits under the board.

• The crosses are the game. Every crown kills a row, a column, a region and its eight neighbours, so mark the dead squares instead of holding them in your head and the board narrows itself.
• Go at the smallest region first. A colour squeezed into a couple of rows forces crowns out of those rows everywhere else, which is usually where the first genuine deduction appears.
• The uniqueness guarantee is a tool, not a boast. Since every board has exactly one solution, an ambiguity you cannot break means you have misread a constraint somewhere, never that you are meant to guess.
• The week has a shape. Boards grow from Monday to Sunday, so the same puzzle asks a different amount of you depending on which day you turn up.