Normal sudoku rules apply. In cages, digits must sum to the small total in the top left corner of the cage (ie the uppermost then leftmost cell). Digits cannot repeat inside cages. BUT the cage shapes themselves must be deduced! The cage can have any shape but the number of digits it contains must be equal to X where X is the digit in the cell containing the total. Cages may not overlap. Clues outside the grid show the sum of all the digits that are inside killer cages in that row or column. The inequality sign means that R3C4 is higher than R4C4.