Normal sudoku rules apply. The values of the cells in a cage must sum to the small clue in the top left corner pf the cage. Digits may not repeat in cages (but values may repeat). In every row, column and 3x3 box, is a “mirrored digit”. It takes the value opposite to its own value on the 1-9 scale. (In other words, 1 takes the value of 9, 2 the value of 8... 9 the value of 1.) Each digit 1-9 is mirrored once.