Don't get me wrong, this is a cool demo, but as someone who experimented with verlet based physics before I don't understand what is so impressive about a basic

Don't get me wrong, this is a cool demo, but as someone who experimented with verlet based physics before I don't understand what is so impressive about a basic implementation in JavaScript. The math behind it is ridiculously easy and JS got faster over the years. And as someone already mentioned there is a 13 years old paper about verlet physics in games so this is everything but new.