Nepukadnezzar said:
And for Bara_no_Hime (does this name mean princess something?) it would be nearly impossible to write a game like that without being a visual novel with pretexted answers to pretexted problems. If it was possible to pull of a greater problem and various ways of solving with AI reacting to it, it would be awesome. Or just so many pretexted possibilites that nobody would care if it is pretexted (does the word pretexted exist?)
Well, Planescape Torment did a pretty good job of allowing you to problem solve entirely based on dialogue. Yes, there's a combat engine, and yes you can ALSO fight most encounters rather than talking through them, but it is perfectly possible. You just have to put in a TON of dialogue.
A game without voice acting (or minimal voice acting) would be a must. In modern AAA game design, that's practically insane, but it is probably how it would have to be.
As far as getting bored - well, too bad. Yes, it would bore some players. If you were looking for something filled with action, this game would not be it. This game would be closer to a visual novel, but a visual novel is just a choose-your-own-adventure book. This game would have quest lines (like Skyrim) with branching dialogue trees. It might have a text-heavy element LIKE a visual novel, but it most certainly wouldn't be one.
Plus, you WOULD have other abilities. Stealth, for instance, for spying. If you got caught, you'd have to talk your way out of a situation. If you failed, you might be asked to leave, you might reveal to the enemy that you've heard their plan (causing them to change it?), or you might be publicly shamed, making it harder for you to talk people into things in the future.
As far as the dialogue trees go, perhaps something like the Deus Ex conversation challenge system? It was (very) flawed, but it was a good idea at the core.
Ideally, this would be a project to start small. An Indy title where voice acting isn't expected. And one where a focus on writing wouldn't go amiss.