Ah, adaptive difficulty. Nothing makes designers happier, and players angrier, then a game that scales to meet exactly the player’s needs. And it’s a natural benefit (or curse) in procedural storytelling. Players just don’t want to hear that the game is gaming them back. They don’t want to be reminded that a computer is pulling the strings, outsmarting them in a sense, even if it is “for their own good”. At least when a designer lays out the level it’s a human doing it! This is a tough problem, but I think you can approach it 2 ways. Either you approach it as an AI problem (yes, the computer is better then you), or you approach it as a perception problem (this is just how the game was made).
I prefer the latter, but it’s not exactly the same, and it requires a few tweaks. The same kind of tweaks you’ll find in “bad” AI. I think the key is to make the difficulty laggy, like it’s reacting in “real” time as opposed to instantly. In practice, this is good anyways, because in procedural space we’re dealing with discrete fixed difficulty blocks anyways, “encounters”. What this means is that the player can always be “better” then the system. And it can clobber them for getting sloppy, for a little while. I think it also helps to have “tiers” if you’re in an RPG space, an area where the player knows the difficulty ranges between here and there relative to their own level. Consider Diablo 2’s Acts as an example. This has the effect of the player telling the designer what difficulty they want to be challenged at. The more ways you can do this, the better. Just don’t take it to the level where the AI responds immediately. The World Ends With You dynamic leveling setting is brilliant at this – to the point that it’s not really adaptive difficulty at all.
And of course, that’s always the final option. You don’t really need adaptive difficulty based on player intent to do procedural storytelling. You could progress the difficulty based on time passed, or the meta-arc, or the stage in the current story arc. In fact, you absolutely should progress it based on the micro story arc, because this contributes to the story’s tension and builds to a climax. But that will be my next topic.