A free program for Android, by Chess King.

The program is based on a textbook by Victor Golenishchev. It consists of a course for intermediate players, based on a source material of more than 290 examples of play by lead chess players from the latest major contests.

In the course, you can find 34 themes, including the theoretical and practical aspects of the game, as well as the questions and answers. There are more than 750 exercises of varying difficulty, and the program acts as a coach, giving you hints, explanations, and showing you even striking refutations of the mistakes you might make.

In addition, the program contains a theoretical section, which explains the methods of the game in a certain stage of the game, based on actual examples.