The app is designed specially for playing audio books.
Assumed that you have audiobooks and already copied them to your phone.
First 30 days Full version. Later - Basic version.
Features:
Chromecast support.
Playback speed control.
Classification of books (new, started, finished).
Download cover from the Internet.
List of characters. You can manually create a list of characters to easier follow the story.
Automatic pause in case you fall asleep. To continue playback just shake your phone.
Playback history.
Application Widget. Allows you to control the player from the home screen.
By specifying a root folder containing all your audiobook, you can exclude your folders which contains music and other audio files.
You don't have to finish one book to start another. The progress is saved independently for all books.
NO ADS!

To purchase (restore after reinstalling) full version press:
menu--Help--Version tab
Phone must be connected to the Internet.
Full version cost is $2.

Many thanks to people who left comments and suggestions.