✔ Complete tutorial that shows you all the tricks to solve sudokus, valid for both beginners and experts. ✔ 5 perfectly balanced levels of difficulty: Easy, medium, hard, very hard and extreme ✔ More than 5,000 well-formed puzzles. ✔ 9x9 grid. ✔ Lots of different designs, choose your favorite. ✔ Unlimited Undo/Redo ✔ Auto-Fill Notes Option ✔ Auto-Clear Notes Option ✔ Advanced game options and notes ✔ Full game is free, with very few ads. ✔ Highlight duplicates to avoid repeating number