How to play
Kurodoko — 黒どこ — or Kuromasu is a logic puzzle.
- Every cell ends up either white or black.
- A cell with a number in it is always white.
- A number is how many white cells it can see in a straight line — up, down, left and right — counting itself. A black cell or the edge of the grid stops the count.
- Two black cells never touch side by side. Corner to corner is fine.
- Every white cell must connect to every other white cell.
Tap each cell: mark it white > fill it black > clear it.
On the name
The full Japanese name is 黒マスはどこだ (Kuromasu wa doko da, “where are the black squares?”), shortened to 黒どこ (Kurodoko) or 黒マス (Kuromasu). English-language puzzle books use both Kurodoko and Kuromasu for the same puzzle. It was published by Nikoli.
The rules in full