- ➊ Blacken some cells of the diagram [paper] resp. color the
gray cells of the diagram black or white [interactively].
- ➋ Cells with numbers must not be blackened. Black cells must
- ➌ Starting at a cell with the number N exactly one of the
cells with distance N must be blackened.
- ➍ All white cells must form an
orthogonally contiguous area.