Killer Sudoku is a variant of sudoku in which the clues are provided in the form of sums of cell groups. Depending on the solver's skills at mental arithmetic, Killer Sudoku can be easier to solve than a regular sudoku. KILLER SUDOKU X is the more difficult one of this variation.

Vasbyt-Sudoku - die Engelse Killer sudoku - is 'n wisselvorm van sudoku waar die leidrade in die vorm van som totale in groepe selle verskaf word. Vasbyt-Sudoku is vir mense wat bedrewe is in hoofrekene. VASBYT-SUDOKU X is Vasbyt-Sudoku se moeiliker boetie.