Meet Ruffle, an open source Flash Emulator. With 99% support for Actionscript 1&2 and 90% support for Actionscript 3, it is surprisingly robust and mature. Gone are security and performance issues that used to plague the original plugin. And no need for visitors to install anything. To bring your old Flash Creations back to life (or create completely new ones!), just add a single script tag to the html page that contains your SWF:
<script src="https://unpkg.com/@ruffle-rs/ruffle"></script>
I was able to revive my old band site and a number of old animations and games. And Steve Jobs would have hated this, but it even works on mobile!
In the early Flash days, British creative agency Hi-ReS! was one of my biggest inspirations, and recently they revived their old Flash work using Ruffle. Do check out their website for Requiem for a Dream.