Play a crossover variation of Sudoku and Kakuro! SumSudoku, also known as Killer Sudoku, are addictive logic puzzles best described as a cross between Sudoku and Kakuro. Using pure logic and simple add/subtract calculations, these fascinating puzzles offer endless fun and intellectual entertainment to puzzle fans of all skills and ages. Each puzzle consists of a 9x9 Sudoku grid containing areas surrounded by dark borders. The object is to fill all empty squares so that the numbers 1 to 9 appear