Text-based UI that is smarter than the conventional command line.
With Zork you somehow have a (seemingly) plain-English conversation with the computer that takes you through a fictional setting and story.
With Inform7 you write the scenario in what looks like plain-English (eg. "The shed is north of the building") and it compiles to a Zork-compatible runtime engine.
Inform7 uses a number of "clever" tricks such as accepting the word "seven" for the number 7 that are unusual in software practice, not conceptually deep, but contribute to the illusion that you're writing English. The rules engine is half-baked but confronts head-on the problem that "commonsense knowledge" that it is mostly built around defaults. (eg. by default you can not pick an object up, but if an object has the "portable" attribute you can pick it up, unless it is a bird statue that will turn into a real bird and fly away when you try to catch it unless you are wearing the medallion)
The author of Inform7 would like to enable English majors to write interactive fiction and the success there is still partial because once the story gets complex enough the authors have a hard time understanding why the system does what it does.
The author of Inform7 is plugging away at it, maybe somewhere somebody else is building something similar out of stronger wood. I was talking with a European aviation regulator who would love to see "Inform 7 for business rules".
It is much easier for rules in this kind of system to be readable by subject matter experts than writable, but readability is a big plus -- if you can show the rules on
a slide and a get a check-off that is a great way to keep in sync.