The Plot of the Phantom, a text adventure that took 40 years to finish

Nice job. I think it might be worth adding a few more verb synonyms to make the parser a little bit less strict - what's a few more years of development. :)

Like many other devs I also dipped my feet in the world of interactive fiction. As a kid I was just learning about concepts such as inheritance / OOP / etc. so I went a bit overboard on the ontology.

I remember pretty early on making a rather large mistake in that regard when a friend who was beta-testing the game for me at the time typed in commands like "get key", "get sword", "get ye flask", and then "get Aldwin" to which the game merrily replied "OK" and promptly stuffed an entire human being into the player's inventory.

Heh. I remember similarly spending a few hours inside LambdaMOO. Successfully managed to clone myself, put myself in my clone’s pocket, and then put my clone in my own pocket and kind of broke room reversal. It was only later I discovered this was an intentional mechanic/bug that some designers that used to create very, very difficult puzzles.

Weird things happen when you give your MOO players a REPL in LISP land.

I remember writing one of these and typing "put bag in bag" and then being confused why the bag disappeared from the world.

Should have done it the other way around

This was a long running bug with merc based muds. The logic was to scan the room items first which cased the bug. Later versions would scan corpses first, then self, then room.

Much better to have the world disappear from the bag.

put bag in bag of "things which do not contain itself"

Russell's Paradox: https://en.m.wikipedia.org/wiki/Russell%27s_paradox

I once wrote an (Amylaar LPC) enemy who, if you attacked him and he was near death, would summon two comrades to fight for him.

Unfortunately, they're immediately hostile so you start attacking them too, and _they_ get near death and summon two comrades each, and so on. It turns into a Sorcerer's Apprentice scenario very quickly.

I managed to bring the MUD to a halt. An archwizard (not Yen Sid) had to instakill the enemies to avoid hitting their "near death" condition and creating more of them.