Sensei Sudoku! app for iPhone and iPad

Sensei Sudoku is the classic Sudoku puzzle-solving game with a modern look.
FEATURES:
- There are thousands of valid puzzles with unique solutions,
- 6 different puzzle difficulties: BEGINNER, EASY, MEDIUM, HARD, EXPERT, LEGENDARY,
- Three different input alert modes: 
1. Never alert, 
2. Alert when the input is blocked by other cells, 
3. Alert when the input is wrong,
- Manual note-taking mode,
- Automatic note-taking for one cell or all cells,
- Direct filling mode,
- Isolate filling (cell painting) mode that highlights possible cells,
- Haptic feedback,
- Unlimited undo,
- If you cannot solve a cell, use unlimited hints,
- 4 different color themes: Ice, Candy, Coffee, Mint,
- Multilanguage support,
- Auto save,
- Inverting the notes of a cell: For example, if it is easier to note down the numbers that cannot be a candidate for that cell, you can invert the notes.