I was thinking of adding a query system into my game that allows the player to query for information about the world through NPCs, books and libraries.
For example there would be a "Query" action associated with NPCs where you could enter a keyword and the NPC would either say "i've never heard of X", or would spit out information about it. The keywords would be simple single names for things so there would be few parsing issues.
The chance of an NPC knowing about a given keyword would depend on how commonly known the information was and the NPC type (eg a weaponsmith is more likely to know more about a weapon than a farmer). Their knowledge also determines how much detail they can provide. This would be useful for figuring out if certain plants were edible or poisonous, what certain potions do, more information about specific monsters, etc. But the main reason I was thinking of doing this was to allow the player to research their own sidequests.
Here's an example of what might be possible:
You find a history book for sale in a village. It's a long boring procedurally generated list of events that have happened in the history of the world. One of the passages mentions a powerful magical item called the Moon Scepter. That might still be around somewhere right? You query the villagers for that term to see if they've heard of it. None of them have. In inspiration you go and ask a local scorceror, who might know a bit more about legendary magical items... He recalls a legend that the scepter was made by a cult which was hunted down and destroyed in their temple in the valley of shadows, but he doesn't know where that is.
You decide to journey a long distance to the city where you can ask a cartographer where the valley of shadows is. You also access the large library in the city where you discover the necromantic powers of the scepter and how the king sent an army to destroy the cult that built it. The scepter itself was never found.
From a cartographer you learn the valley of the shadows is in the far north. Very dangerous location, so you get supplies and hire two mercenaries and head out. A bunch stuff happens on the way involving hostile creatures, but you make it north with both mercenaries.
In the north you ask local villagers if they have heard about the valley of shadows but it is made clear that they are hiding information. You eventually bribe a villager who tells you the location of the valley of shadows and the abandoned temple in it. You decide to head out.
On the way you are ambushed by half a dozen human attackers. Thanks to your mercenaries you survive. You find a note on one of the attackers reading: "three outsiders have been talking about the valley of shadows. If they head out that way kill them". You continue heading for the temple, but now it's clear the place is not abandoned.
At this point you now have a dungeon and a quest item to fetch, but the quest itself is more personal because the player has made it for themselves. It hasn't been forced on them through a sidequest by some mage in the city who simply tells you "Fetch me the Moon Scepter from the Valley of Shadows (5000XP)". Also the world is able to react to what the player is asking about - eg planning that ambush.
Technically this doesn't seem too much of a big deal to do, it's a lot of work but it isn't complicated AI. It's just a keyword search sitting on top of procedurally generated names for weapons and places and linking references together so that each library or book would have a hidden set of keywords they would respond to and would only reveal limited info about it.
The only thing I worry about is that this searching by keyword of NPCs and books will make the game too boring - it might feel a bit like using google search in the game all the time. I am aware from experience that ideas I think are fun initially can turn out to be unfun, so I just want to check whether it passes the smell test for other people.