Queens

One crown per row, one per column, one per color — and no two crowns may touch, not even at the corners. Tap a square once to cross it out, again for a crown, again to clear it. Drag across the board to cross out a run of squares in one go.

Every board is generated in your browser and checked to make sure it has exactly one solution, so there is always a way through without guessing.

Stuck? Hint spotlights the row, column or color where something can still be worked out and tells you what holds there — press it a second time and it plays that move for you. Undo walks back a move at a time, and a whole drag counts as one.