For sudoku fans looking for a new puzzle to delight and challenge them, Will Shortz, the crossword editor of "The New York Times" and America's puzzlemaster, presents kakuro. If you've never tried these deceptively simple-looking puzzles, get set: Millions of puzzlers around the globe are already hooked The object is quite simple: Place a single digit from 1 to 9 in each white square of a crossword-like grid. A clue number, shown in a shaded square,...