This project was started in 2014, and slowly continued into 2016. The code found here was part of a tutorial series found here on the CodeNMore channel. Remember that the code here is not the only way to do something, and the final video of the series discusses some of the good and bad design decisions made while creating this project, how it can be improved, and how developers are constantly learning.
An updated series can be found on the CodeNMore channel utilizing the LibGDX game engine as of mid-2020.
The source code for each episode in the series can be found here. Look in this repository and select the folder that corresponds to the episode number you are looking for. Within that folder is my own Eclipse project folder, though you don't need Eclipse to view any of the source code or run it.