KuroMasu Puzzle 黒マス

(Where are the black cells?)

Place 20 black squares on the board to solve the puzzle.

			6				5
	9				7
3						9
		3						3
	8				7
6							6
		6		7				5
	4				3
			2			6

Easy
Puzzle Medium
Puzzle Hard
Puzzle Check
Answer See
Solution

How to Start
Have a look at the numbers given in the 18 clue squares.

Each clue square shows the number of white squares that can be seen from that square looking along its row, left and right, and column, up and down, including the number square itself. Placing a black square blocks the view to make the numbers correct. The three rules are:

Numbered square may not be black.
Black squares must be not be side by side or one above the other. The closest is diagonal.
All the white squares must be connected horizontally or vertically.

To place a black square click or tap on the square. To turn it back to white if you need to, just click or tap the square again. Remember you need 20 black squares on the board.

You can Check your Answer when you have placed all the black squares. Mistakes are shown in red. You can See the Solution below if you really do give up.

History This puzzle was published by Nikoli in March 1991. Nothing more is known. Latest news: there are Apple and Google KuroMasu apps for smartphones.

You may also discover a puzzle called ‘Nurikabe’ which also has numbers and placing black squares. This appeared in the next issue of the Nikoli magazine but I think it is not as good as KuroMasu.