I’ve linked the sudoku page, but if you scroll down, there are dozens of other puzzles and they’re all well-implemented and free with plenty of customization options, difficulty levels, leader boards, etc. I patreoned the dev recently. He’s very responsive to any bugs, and considers, for example, a puzzle with multiple solutions to be a bug. He also adds new puzzles fairly regularly.
https://www.puzzle-sudoku.com/
I’ve linked the sudoku page, but if you scroll down, there are dozens of other puzzles and they’re all well-implemented and free with plenty of customization options, difficulty levels, leader boards, etc. I patreoned the dev recently. He’s very responsive to any bugs, and considers, for example, a puzzle with multiple solutions to be a bug. He also adds new puzzles fairly regularly.