Sudoku presents the classic game in a digital format that's accessible and attractive, making it easy to take your puzzles with you wherever you go. Through the app's intuitive interface, you can play as many puzzles as you want of various levels of difficulty, and you can see how you stack up against your friends and fellow players through Game Center.
Note mode: Since this app scores you based on how many mistakes you make in number placement, you can't randomly try numbers in game mode to see what fits. Fortunately, you can switch any time into note-taking mode, which lets you place temporary numbers in blank spots on the puzzle without telling you whether they're right or not, but also without penalty. Once you've got your numbers where you want them, you can switch back to game mode and place permanent tiles over the note numbers, which are still visible.
Totally free: This app is free to download, and there are no in-app purchases offered. That means that you never have to worry about having to pay later on for more levels or anything else. There are banner ads always on the screen, but they don't interfere with the gameplay experience.
Note toggle: While the note-taking feature in this app is definitely a plus, it would be nice if there was a little bit of a difference between the note-taking screen and the regular game screen. The lack of any visual clues to tell you which screen you're on means it's possible to think you're in note mode when you're really in game mode, where you can be penalized for improper tile placement.
Anyone who enjoys Sudoku will love this app. And even if you've never played the game before, this app gives you a great platform to try it on.