Normal sudoku rules apply. The grid is partially covered in fog. Placing correct digits reveals clues in the surrounding 3 by 3 area. Digits an equal distance from the centre of a lavender 'Zipper Line' must sum to the digit in the middle of that line. All Zipper Lines are 5 cells long, only move orthogonally and can't share cells with other Zipper Lines. Digits separated by a white dot are consecutive. Digits separated by a black dot are in a 1:2 ratio (ie one digit is double the other). Not all dots are given.