The application contains more than ten player and hundred grandmaster games in total.
These players:
Magnus Carlsen
Fabiano Caruana
Ding Liren
Jose Raul Capablanca
Robert James Fischer
Paul Morphy
Wilhelm Steinitz
Viswanathan Anand
Wesley So
Hikaru Nakamura
Sergey Karjakin.

The application simply works like this:

You choose the player and the game you want to study.

Then you try to guess the grandmaster's move in position or the best move in position.

The app then gives you a return score. This score indicates how good the move is.

Then it plays the move played by the grandmaster in the game and asks you to guess the move again.

This way you will be able to practice played classic chess games by masters.