Learn advanced tips and tricks to solve difficult kuromasu puzzles. When you have learned our solving techniques, then you can try to play kuromasu online.

When you start solving the puzzle, look for cells that can not be reached by any numbered cells. These cells can be made white. This will help you in conneting thse cells with other white cells.

The cells without numbers that are marked white in the example below (D3, C5 and D5) are cells that can not be reached by the numbered cells.

This technique refers to the first rule that every numbered cell on the board must see that number of white cells.

For each numbered cell count the number of cells in all directions until a black cell or the side of the grid is reached. Repeat this for all sides. Add 1 for the numbered cell itself. If the total matches the number of the cell, all cells those cells may become white cells.

When you do this with number 3 in the example below, then you get 9 instead of 3. So this method doesn' work for this number. The same goes for the numbers 2.

This technique also refers to the first rule that each numbered cell must see that amount of white cells.

If the number of white cells match the number in the numbered cell, then the cells next to each last white cell will become a black cell or the side of the grid.

Let's use this technique with the puzzle below:

- D4 must be white (rule: black cells may not connect horizontal or vertical).
- C3 must be white to have enough white cells.
- Now we need one more white cell (B3 or E3).
- It can be E3 because then B3 woudl become black with the result of 2 vertical black cells (B3 and B4) what is against the rules..
- So B3 is are last white cell.
- And last but not least: now A3 and E3 become black cells.

One of the rules says: two black cells may not connect horizontally or vertically.

So we scan the entire puzzle and check all 4 sides for each black cell. All the cells connecting horizontally or vertically with a black cell must become white.

If a row/column of white cells is interrupted by an empty cell, than count this cell to be white. If the total number of white cells is now larger than the number in the numbered cell, this cell will have to become black.

If cell C3 becomes white, then the numbered cell D3 (with number 4) connects to 5 white cells which is one cell to much. So C3 must be black! And now D1 and D2 become white.

The side of a cell is fixed when there is a black cell or white cell(s) followed by a black cell or the side of the grid. If the side of is cell is followed by the side of the puzzle, than that side is also fixed.

When a numbered cell has 3 fixed sides, than the 4th side can be calculated.

Cell B3 and cell C3 will become white and cell A3 needs to be black. Now A2 and A4 become white because A3 is black.