Besides allowing you to follow a game, and flip the board around etc, this setup is interactive.
As you follow one of these games, you might wonder "what might happen if...".
Well this setup allows you to do that.
Simply drag and drop the piece and the board position will be changed accordingly.
The computer simply ensures that moves are legal - it does not calculate how good (or bad) a move is.
You have to decide that for yourself.
And when you want to go back to how the game actually went, simply click on the relevant move or rewind the game to the start.
It's your choice.