About Crowns

A square grid split into coloured regions, as many regions as rows. Place a crown in every row, every column and every region — exactly one in each — so that no two crowns touch, not even at a corner. That is the whole rule, and on an eight-by-eight board it makes a proper puzzle.

Every board has exactly one answer, and every one is checked by a solver that uses only reasoning a person can do, so no board ever needs a guess. The reasoning starts simple — a region only one square wide has to have its crown there — and builds: a region that lies entirely within two rows claims both rows' crowns, so nothing else in those rows can have one. Tap a square once to cross it out, twice for a crown; drag across squares to cross out a whole run. Crowns that break a rule turn red straight away.

Auto-cross, if you switch it on, crosses out everything a new crown rules out. A hint puts a crown in the right place — or points out one in the wrong place — for twenty seconds. The daily board is eight by eight, the same for everyone, ranked by time; free play deals six, eight or nine squares a side.

Tips to win

• Start with the smallest regions: a region of one or two squares has few places for its crown
• If a region lies in one row, no other square in that row can have a crown
• The squares round a crown are always out — cross them straight away
• Two regions squeezed into the same two columns claim both columns' crowns