First of all, please keep in mind that the point of this series is not to provide you with the code for a game, but to teach you how to make games. I'd encourage you to use the source code here for reference only.
This is for my java game programming tutorial series that starts with this 7 hour video!
Use the Git tags in the top left of Github to switch to the lesson you want to see source code for.
For example, to download the ZIP for lesson 3 (which is how you get started), go to where it currently says "master" in the top left, then go to "tags" and select "Lesson_3"
Then, on the right where it says "Code" go to "Download ZIP"
Enjoy!