Sudoku X 

Sudoku X is a puzzle game created for Mac where your objective is to fill a 9x9 grid with numbers from 1 to 9. The app has an intuitive and colorful interface, provides you with detailed gameplay instructions, and gives you access to plenty of useful hints.

Each row, column, and 3x3 sub-grid must contain all of the digits from 1 to 9. The numbers shouldn't appear twice in the same row, column or in any of the nine 3x3 subregions of the 9x9 grid. This app lets you know if you entered a digit in the wrong empty cell.

Sudoku X lets you play in a fullscreen or windowed mode, adjust background music and sound effect volume, and access the gameplay instructions at any time.

Another advantage is the fact that you can use the Hint option at any time. By clicking it once, it immediately fills an empty cell from the board. However, your score gets smaller each time you use this feature.

Two things bother me about Sudoku X: it plays repetitive background music and you need to restart the app in order to start a new game.

To cut a long story short, the game comes in handy whenever you're on a break from work and wish to put your puzzle solving skills to the test. So, you should try this app if the aforementioned flaws don't mean much to you.