A free app for Android, by CoolmathGames.com.

Sudoku is one of the most popular logic puzzle games in the world, which is designed to test your brain, mind, and logic. 

The objective of Sudoku is to complete a given puzzle with numbers from 1 to 9 in a 9×9 grid. You must place the numbers from 1 to 9 so that each row, each column, and each 3×3 square has no repeated numbers.

The game has been played for thousands of years and has been a part of culture and tradition in many countries.