Kurodoko (also called Kuromasu) is a Nikoli logic puzzle genre.

  • Shade some cells on the grid.
  • No two shaded cells may be directly adjacent.
  • All unshaded cells must be connected.
  • Clue cells must not be shaded, and represent the total number of cells in the union of orthogonal lines of unshaded cells from the clue cell (including the clue cell itself).