Here's the original 2013 source code for drawing Yoyle City, which appears at 2:27 in https://www.youtube.com/watch?v=RZB7nTzSl3g&t=207s
I wrote it using Processing 1.5.1. https://processing.org/
It may or may not work with more recent versions of Processing - I'm not entirely sure. Running at full resolution / full graphics, it takes about one minute to draw one frame of Yoyle City (that is extremely slow, I know, but it wasn't designed to be a fun game to play, it was designed ASAP in one week for a silly YouTube video!)
Also, I didn't write this code with the intention of ever sharing it with other people. I was 16 at the time and was just doing it to create graphics for the YouTube video of the time. So, it's not designed to be user-friendly at all, which means it's probably really hard to read. :( So, venture at your own risk! Oh well
Anyway, here's a 2016 video where I talk about the code, behind-the-scenes, a bit further: https://www.youtube.com/watch?v=y0nsXiI_I9c