Imagine a situation like this, is D:OS, there is a dialog sequence, where you ended up have this following typical situation.
"Did you slay the monster and avenge my son's death?"
Normally, a modern RPG won't ask you this, it's on a check list, automatically checked off and gives you exps. But say in D:OS you might be able to do the following:
1. lie about it( roll check against charm, bear the consequence if you don't actually kill the monster.)
2. tell the truth and give up evidence( like a +10 stat monster eyeball. )
3. demand more reward
4. kill the client( assuming that the monster is cursed by the client and ask you to help instead.)
So without reveal these choices upon dialog( ie. 4 might be hidden if you don't understand monster language or didn't do enough dialog with related NPC.) It would require a machine like IBM's Watson to understand nature language( remember we have several language ports), and related story info to determine the context you just input. In example 1/2, how are you intended to implement this?
player might type:
"I killed it, now give me my money!"
"It was a easy task."
In above 3 situations, game won't be able to tell if you mean 1 or 2. but can easily done, if you have high enough charm to show first choice.
I'd like to hear if you have better approach to this problem.
Hmm... that's an interesting example. To be honest I don't know if that sort of thing would be a candidate for what I'm talking about; killing a guy seems like enough of a brute force tactic that it wouldn't really make sense as a hidden or secret option.
Also, just to clarify: I meant the player would type a single keyword, and not an entire sentence like "I killed it, it was an easy task" or something like that. Basically the player would be able to enter topics (via single keywords, one word per topic) that aren't displayed on the list, but are still available to talk about "under the hood".
Here's an example where I think this might work (I admit I'm getting this example from another game that most here have not played, but I'll generic-ify it enough that it won't matter):
Say there's an angry guy who sits outside his house all day (and is a shut-in at night -- schedules are in, after all!) and yells angrily at anyone who passes by. As far as most people know, including the player, this is just some angry older crank with a funny nickname who doesn't like anybody. However, perhaps there is a history book, or a townsperson with a bit of info, that can lead the player to realize that this angry guy was actually a personage of some importance, whose accomplishments went unrecognized, or someone else stole the credit/glory from him, what have you, and he's been bitter ever since. By going up to him and telling him his real name as the keyword, you might get him to open up and tell you about his past. The quest might finish there, or keep going onto another section, but that's the basic framework of what I'm thinking of.
Here is the key difference between this kind of quest being built around topic list vs a text entry: with the former, the game "detects" that your character has learned this guy's name and makes the topic show up the next time you talk to him. With the design I'm thinking of, the revelation would be a lot more subtle -- the book or townsperson wouldn't outright say "oh, that cranky old guy actually used to be this other guy, his real name is _____" -- instead the source of info would only allude to the information in a way that the player has to piece it together themselves. Maybe the townsperson could describe an article of clothing, and if you were to sneak into the old guy's house at night, you'd see an old worn version of that same article of clothing. Or something along those lines.
Under this design, making the name show up on the topic list defeats the purpose of making the player figure it out, and leads them by the nose too much. Instead, letting there be a place for the player to enter the name once they figure it out gives a way for this little story to open up naturally. It's another avenue for discovery and exploration, but NPC-centric instead of environment-centric.
There are many other possibilities of course, maybe asking characters about events or topics that one wouldn't normally expect to show up on their topic lists, but that they might have something to say about anyway. There's lots of directions something like this could be taken in.
(Also, one more clarification -- I only bring this up as possibility in the modding tools. I don't really expect Larian to design the vanilla game with a feature like this in it; it would just be cool if a feature like that were available for modders to use in their own works.)