Looks like it’s decidedly not open https://github.com/ganelson
I believe the “opening” is to be understood as present progressive form.
It’s being staged to be open sourced this fall, I believe.
Interesting read. I was not familiar with Inform before reading this. I like that the designer(s) use Literate Programming, and I’m interested to read the current state of that paradigm (at least according to this presentation).