Unlike ordinary sudoku apps, this particular software is your companion and helps you with solving sudoku tables. It helps you better understand the underlying structure of a sudoku game.
When you select a number for a cell, this app, shows you the consequences, then you take another step and so do the app. Eventually you end in a failure state, app marks the problem out for you and provides you with an undo button by which you can go back and take another action....
This way you virtually traverse the state tree of the game.