- Blacken some cells of the grid [on paper] or color the
gray cells of the grid either black or white [interactively].
- A number in a
region indicates how many cells in this
region must be blackened. In regions without
a number any amount of cells may be blackened (maybe none).
- Black cells may not be
orthogonally adjacent (diagonally
is allowed).
- Stripes of adjacent white cells may not span across more
than one region border horizontally or vertically.
- All white cells must form a single
orthogonally-connected area.
Additional Rules:
Regions with the same number of black cells may not touch each other, not even
diagonally.