Mensa members are known for their finely-honed logic skills—and that’s just what it takes to become an expert at sudoku. So it’s no surprise that this organization for the highly intelligent has put together a huge collection of these sizzling-hot puzzles—a whopping 534 games to sate the obsessed solver’s craving. They start out relatively easy for the newcomer, and get harder (and more fun!) as you go along.