Normal sudoku rules apply. In cages, digits must sum to the small clue in the top left corner of the cage. Digits cannot repeat within a cage. Cells that appear in the same relative position in their 3x3 box must not contain the same digit. eg the digit in r1c3 cannot appear in r7c6 as this would cause a repear in the North-East corner cell of the 3x3 boxes.