yukendo is an addictive puzzle game that shares many concepts with sudoku, but adds some variety to the well known gameplay. Easy to learn but difficult to master a game for puzzle fans and number crunchers.nnThis is what the reviewers think:n"I really like the formula that KENKEN invented, and Yukendo Pro takes it one step further in terms of difficulty. You also get global highscores, and Facebook connect to add gamelife"n touchgen.netnnyukendo offers difficulty levels for beginners and advanced puzzlers. Whether you have never played a similar game before, or have been playing Sudoku for years, you will find the right challenge.nWith different level sizes you can play a short game on your way to work or a full afternoon. You can't finish a puzzle in one go? No problem your game get's automatically saved. If you are stuck, save your game, try an easier one and come back to it later.nWith local and global highscores, you can compete with your friends and the whole world.nnIt is also a great way to learn mathematics. In fact the game has been invented by Tetsuya Miyamoto to teach his pupils maths. He called it KenKen which means cleverness squared in Japanese.nnFollow these easy rules and get hooked in minutes:n1. Fill the grid with digits 1 through 4 for a 4x4 grid, 1 through 5 for a 5x5, etc.n2. Every digit may only occur once per row and column.n3. The grid is also divided into cells the numbers of each cell must produce a certain target number when combined using a specified mathematical operation either addition, subtraction, multiplication or division.nnEvery grid of yukendo has at least one solution.nnyukendo is free and offers many hours of fun. However, if you are an advanced player and want to get the full experience, get yukendo pronnStill not convinced? Go to http:apps.rapidrabbit.deyukendo to see the trailer