So, far and away the greatest utility I have found for ChatGPT is in two areas:

• Brainstorming ideas like a random generator or book of tables. ChatGPT can be especially helpful with brainstorming ideas if your campaign doesn't fit neatly into traditional genres or stories typically featured in role-playing games.
• Brainstorming how to tie up loose plot threads. This is beyond the ability of most traditional tools or aids to help with, and it's a godsend if (like me) you often lay down clues long before you've fully worked out all the details of the mystery.

General Brainstorming

ChatGPT is pretty good at just coming up with ideas for your campaign in general. I'm talking about stuff like adventure ideas, encounter ideas, descriptive details of rooms, etc. It's not great, though, and its output can feel pretty generic compared to material like Raging Swan Press which has entire books full of wonderfully evocative tables great for filling environments and dungeons with detail. There's also stuff like this Random Adventure Generator by @slyfourish@ttrpg.network or this other Random Adventure Generator by donjon which are both probably just as good or better than ChatGPT in general at brainstorming adventure ideas.

Where ChatGPT shines however is that you can give it basically arbitrary thematic or fictional constraints and tell it to generate ideas within that context. ChatGPT is mediocre at generic D&D or traditional fantasy, but my campaign isn't a typical D&D campaign world, and as a result ChatGPT is basically the only random generator that can reliably generate ideas that are actually useful for my campaign. In essence, ChatGPT is a random generator I can tailor to my campaign world.

Here's an example below of how I might use ChatGPT for this. In practice, I often like to "prime" it with details of the major characters of my campaign as well. It's not brilliant, and you can see in many places it's effectively repeating back themes or ideas that I gave it in the first place, but it's nonetheless incredibly useful compared to the kind of stuff I tend to get back from other random generators that focus on generic fantasy content.

My biggest challenge with this kind of usage of ChatGPT is that it tends towards sounding like a back-of-the-book summary of a plot, often generalizing or otherwise glossing over the specific details that I'm precisely interested in. The first response to my prompt in the example is a great demonstration of this, which is why you'll see I have to follow up by prompting it for specifics about the McGuffins and the cast of characters. If anyone has ideas for prompts that can avoid this tendency to summarize without making it write novels of text, I'm all ears.

Tying Up Plot Threads

ChatGPT can be really helpful with brainstorming not just general ideas but specific plot points for your adventures and campaigns. I don't know how to explain this well outside of sharing another example but the gist is that you give ChatGPT a lot of detail about your campaign and its themes, characters, world, and setting, and then explain how there's a "gap" in the story somewhere and ask it to brainstorm how to fill it. In my example here, the "gap" is that I'm missing a clue to deliver some critical information, but I've also used it successfully for other things like:

• "Why or how would character ABC be connected to mysterious phenomena XYZ?"

• "Which of these characters could have summoned the monster, and why?"

• "What is the nefarious scheme this character is planning (which I hinted at in a prior session)?"