Company Stefan Heine created these great apps:
Stefan Heine Sudoku - easy to moderate, Stefan Heine Sudoku - moderate to difficult, Stefan Heine Sudoku - challenging and beautiful, Stefan Heine Sudoku - difficult to extreme, Stefan Heine Sudoku - easy to moderate !, Stefan Heine Sudoku - challenging and beautiful !, Stefan Heine Sudoku - difficult to extreme !, Stefan Heine Sudoku - moderate to difficult !, and others..
