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

I'm not saying having LLMs narrate the entire situation. I'm saying have the LLM sit between gamestate and the player. The LLM is the UI.

Essentially the LLM can see the current game state and possible moves and it's the LLMs job to change the game state and report the current game state to the user (via a well written narrative).

That keeps the world consistent and structured, but the LLM adds enough dynamism to keep it flowing well. You can even make the underlying game state complex as well. Like you can have enemy AI's that actually move through the world too (independent of the LLM).

NPC's running around were a thing even in the 80's, see The Hobbit. That on a ZX spectrum. 8 bit CPU, 48k of RAM. With if6 and Zmachine games for 16 bit and 32 bit computers in the 90's llm's can't even compete.

From Jigsaw, Anchorhead, Curses, Spider and Web to that anagram word puzzle game for Glulx (a 32 bit zmachine cousin), the array of amateur but professional looking games it's huge, really huge.