A free program for Android, by Aleksey Samsonov.

If you are a beginner, we recommend that you start with the easy difficulty. As you get more experienced, you can try the harder levels.

You can choose to turn on the hints and autocheck if you want.

The highlight duplicates option will highlight any number that appears in a row, column, and block. This helps you to find patterns.

The hints option will show you what numbers you should put in the grid to complete the puzzle.

The notes option will allow you to make notes. When you complete a puzzle, the notes will automatically be updated.