I dunno what this GM is doing but I find that ChatGPT (GPT4 particularly) does wonderfully as long as you clearly define what you are doing up front, and remember that context can "fall off" in longer threads.

Anyways, here's a paraphrasing of my typical prompt template:

I am running a Table Top RPG game in the {{SYSTEM}} system, in the {{WORLD SETTING}} universe. Particularly set before|after|during {{WORLD SETTING DETAILED}}.

The players are a motley crew that include:

{{ LIST OF PLAYERS AND SHORT DESCRIPTIONS }}

The party is currently at {{ PLACE }} - {{ PLACE DETAILS }}

At present the party is/has {{ GAME CONTEXT / LAST GAMES SUMMARY }}

I need help with:

{{ DETAILED DESCRIPTION OF TASK FOR CHAT GPT }}

It can get pretty long, but it seems to do the trick for the first prompt - responses can be more conversational until it forgets details - which takes a while on GPT4.