Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.If absolute difference between two digits in neighbouring cells equals 1, then they are separated by a white dot. If the digit is a half of digit in the neighbouring cell, then they are separated by black dot. The dot between 1 and 2 can be either white or black.
In order to get the best gaming experience on smart devices such as smartphones or ipads, the touch screen mode is preferred. On your PC, you can choose keyboard mode or touch screen mode according to your preference.