Just when sudoku fans are getting a bit jaded, along comes an irresistible new challenge--Tridoku! This time, instead of a square, the diagram is a colorfully patterned triangle. And just as in the older game, the rules for entering the digits from 1 to 9 are simple, while the logic required to put them in the right places can be surprisingly tricky. Even budding sudoku addicts can join in on the fun, since the puzzles start out easy before becoming progressively more challenging.