Normal sudoku rules apply. The grey line is a palindrome - the digits on a palindrome line read the same in both directions. The lavender line is a Zipper line - digits an equal distance from the centre of a zipper line must sum to the digit in the middle of that line. The two lines have the same composition of digits. E.g. if one line has two 3s, five 4s and a 9, then so does the other. The order of the digits is not necessarily the same on the two lines. Cells separated by a white dot contain digits whose values differ by 1. Cells separated by a black dot contain digits with a 2:1 ratio ie one digit is double the other. Not necessarily all dots are drawn in.