This is amazing—made even more impressive by the fact that the author is just 15 years old!
Also, it's nice to see this mentioned:
> For this 10k-word write-up, I spent around a month finishing up the main parts, and refining/editing it took an extra while. Writing this is indeed a painful process. I spent the entire day on the weekend and 4-5 hours during the rest of the week working on it for around two weeks.
It's the kind of behind-the-scenes effort that often goes unspoken.