An interesting little application; from what I can tell written in a combination of Logo and Lisp. You can interactively edit the UI, etc. Hit the 'Setup' then the 'Go' button to run the code (the source itself is hidden by the scrollbar in the main window). https://codap.concord.org/app/static/dg/en/cert/index.html#shared=https://cfm-shared.concord.org/iGCemjqgrcHduADPwtMM/file.json (Oh, and it is a virus/Covid simulator)

I'll check it out, but your description reminds me of https://github.com/Hundredrabbits/Ronin

Nope, Ronin is cool, but not the same thing. This is more like a code notebook with interactive widgets.

I see. Yeah. This is quite powerful. Perhaps even too powerful. But at first glance this looks like an end-user programming system! It fits everything I was looking for at https://futureofcoding.slack.com/archives/C5T9GPWFL/p1634445846387500

This is cool! The foundation seems to be this: http://ccl.northwestern.edu/netlogo/