Sudoku - Numbers Game Puzzle

Introduce:
Sudoku is a numerical logic reasoning game that originated in Switzerland in the 18th century. In 1984, a Japanese scholar introduced it to Japan, published it in a game magazine of Nikoli Company, and renamed it Sudoku. This game provides multiple difficulties, experience the advanced road from easy to master. It is a logic game that uses paper and pen to perform calculations. Players need to deduce the numbers of all remaining spaces according to the known numbers on the 9×9 disk, and satisfy the requirements that the numbers in each row, each column, and each thick-line palace (3*3) contain 1-9 without repetition.
How to play:
The Sudoku board is composed of nine palaces, and each palace is divided into nine small grids. Give certain known numbers and problem-solving conditions in these eighty-one grids, and use logic and reasoning to fill in the numbers 1-9 in the other blanks. Make each number 1-9 appear only once in each row, column and palace. There are nine horizontal rows in the horizontal direction and nine vertical columns in the rectangle. It is divided into eighty-one small squares, so it is also called "Nine Palaces".
Features:
Classic Leaderboard: Provides leaderboards with four levels of difficulty. Compete with players from all over the world to see who can complete the shortest time and use the fewest steps.
Skinning function: You can choose from a variety of skins, and there is a night mode, which protects your eyes during night games.
Smart Tips: According to the current progress of the puzzle, it will give clues to solve the puzzle to help you pass the level effortlessly.
Note assistance: Provides blank squares to enter possible answer numbers to help reasoning more smoothly.
Error Erase: Allows you to have unlimited trial and error.
Unlimited Undo: Easily go back to the previous action.