Kaiden Sudoku

This Sudoku ain't free, but it's cheaper than a good meal, and you get all these wonderful features:

* It's yours forever. No in-app payments. No subscription shenanigans.
* No ads. No tracking. No nonsense.
* It works offline. In fact, it doesn't even care if you're online.
* It has an unlimited number of puzzles, in four levels of difficulty.
* It supports infinite undo and redo.
* It has notes, for when you're not yet sure what number goes where.
* It supports gestures:
* Swipe up/down on the board to switch between numbers and notes.
* Swipe right/left on the board to go to the next/previous number.
* Share puzzles with your friends, see who's smarter after all.
* Use your phone's camera to scan printed puzzles and play them in the app.

Have fun!