Nurimisaki
Shade cells so the white cells form one connected region and no 2×2 square is all white or all black. A white cell with exactly one white neighbor is a cape — and the capes are exactly the circled cells. A number counts the white cells of the straight run leaving the cape, circle included. The rule is an iff, so every blank cell is a clue too: it promises no cape here. Click a cell to cycle shaded → white → empty; right-click erases.
The blank cells are clues
Every puzzle in this series clues a board with printed marks. Nurimisaki also clues it with the places where nothing is printed: a blank cell may never end up a white cell with exactly one white neighbor. Half of the solver's opening moves come from that promise — and switching it off multiplies the solution counts of typical boards. The negative space is load-bearing.
The board picks its own grade
In the rest of this series any (size, difficulty) pair exists: start from the full reveal and thin. Here the circle set is forced — circles sit exactly on the capes, so clues cannot be added, only numbers removed. The clue budget is dealt by the board, and it doesn't grow with the board: past 6×6 the cape-graded and window-graded boards simply stop existing. The Rules menu greys out the grades your chosen size cannot produce.
Four rule sets
cape enumerates which neighbor of a circle is its single white one — runs included — and applies the blank cells' promise. window closes 2×2s about to go monochrome. bridge makes white connectivity local with one articulation-point pass: a cell sealed off from the white region can never be white, the only route between two white cells must be. probe assumes a color on a cell and watches the rules below refute it.