Rules of Sudoku puzzle Dots 9x9 #11 (Kropki Sudoku, Dots Sudoku, Black and White Sudoku) to solve online for free
Fill in the grid with numbers from 1 to 9. Each row, column, and 3x3 rectangle contains exactly one number. If the difference between two cells is 1, a white point appears. If a digit in a cell is half of an adjacent cell, a black dot appears. The dot between the two cells numbered 1 and 2 can be either of these two colors.