Don't let the fact that it has only one review* as of this post keep you from downloading this nicely done Sudoku app. It has attractive graphics, pencil notes, an undo feature and hints. If played in landscape mode, a tiny bit of the bottom of the chart is cut off, but it doesn't get in the way of gameplay. If it bothers you, play in portrait mode. This seems a very good Sudoku app to me. I do recommend reviewing the "How To" as the iconography is somewhat cryptic.
Not free, but while we're at it, Amazon has 9 word games on sale for 50% off or more. Don't know how long this has been on, I just noticed it. Both Scrabble and the very popular W.E.L.D.E.R. are reduced to $0.99 from $2.99.
Click here to see the list. Ignore Sleep Sounds if it shows up--unless you want a white noise app!
*the review is five stars and does not appear to be a developer review to me...