-Ordinary sudoku rules apply.
-Killer Sudoku Rules apply. Digits cannot repeat in cages and must sum to the number in the top left (if given).
-Little Killer rules apply. The digits in the indicated diagonal sum to the number indicated. Numbers may repeat along each diagonal.
The killer cages are clues that are needed to solve the puzzle. Some (but not necessarily all) need to be decoded and then read from left to right and top to bottom. To decode a clue, subtract 26 from it as many times as you can without it becoming negative and then convert that number to it’s alphabetical character (1=a, 2=b, 3=c,…)