Livecode used to be opensource, which made me want to use it, but that window closed.
I guess I want a Flash replacement....
https://ruffle.rs/ recently came to my attention when I needed to resuscitate a back into tool that had been completely built in Macromedia products
Unlike LiveCode (or so far as I am aware HyperNext), Decker is free and open-source: https://github.com/JohnEarnest/Decker
Hypernext doesn't appear to be actively developed; the most recent updates I see are from last year. Decker's most recent release was yesterday morning.
I'd be happy to go into more detail if you like.