Hi, thanks for playing the game!
The source is merely a bonus, for anyone interested.
Regarding the book, if you find it hard to understand, perhaps you can make a few Odin programs and then return to it. Since you’re interested in gamedev, then perhaps you can try one of the video tutorials I have on my YouTube channel and then return to the book? For example this one: https://youtu.be/lfiQNCNUifI?si=YfOupaL-H8L90TSs
Have a nice day! /Karl