If you're looking for a challenging Sudoku game, Book of Buffalo by Andrii_dev is the perfect choice for you. Available on Android, this free game is a great way to spend your free time.

The game follows the traditional rules of Sudoku, where a 9x9 square must be filled with numbers from 1-9 without any repeated numbers in each line, horizontally or vertically. However, Book of Buffalo takes it one step further by adding 3x3 squares marked out in the grid, where no repeat numbers are allowed either. This adds an extra layer of difficulty to the game and will challenge even the most experienced Sudoku players.

The interface of the game is simple and user-friendly, with a clear layout that makes it easy to navigate. The graphics are visually pleasing, and the game runs smoothly without any lag. Overall, Book of Buffalo is a great choice for anyone who loves a challenging Sudoku game.