From the world #1 Sudoku site: Billions of free Sudoku puzzles to play anywhere.
• 4 free levels - Easy, Medium, Hard and Evil.
• Check for mistakes with the "How am I doing?" button.
• Play anywhere, pause and resume your Sudoku.
• 'Pencil marking' option for entering possible numbers in a cell.
• Print unlimited free puzzles using Google CloudPrint.
• Compare your time to millions of Sudoku solvers.
Exclusive to the app:
• Unlock Extreme level, our hardest puzzles yet!
• Landscape and Portrait mode supported.
• Play left-handed - switch the numbers and grid.