If anyone else, like me, had no idea what this is even about then I found
https://www.pouet.net/faq.php.
So it seems it's a bunch of demos from the 90s (or written for 90s hardware) running on emulators in the browser.
I used to have an Amiga back then, and I remember the demo scene. They basically wrote programs that would push the limits of the hardware to demonstrate what is possible. Some of them were quite mind-blowing as they would seemingly do stuff that you would know, from playing games, was not possible.
