Sudoku for beginners

This is a simple Sudoku with focus on the game:- no ads,- no timer,- no sounds,- no fancy distracting stuff,- simply enjoy the gameIt packs some features that are useful for beginners:- several difficulty levels- easiest level has a hint button (press it when youre stuck)- colors for the numbers- remaining numbers indicator- note taking mode- unlimited undo levels- rules of the game are explain