Honestly I'm really excited about this. I've always dreamed of full blown sandbox games with extremely advanced NPCs (which the current LLMs can already kinda emulate), but on the bigger scale. In just a few decades this will finally be made into proper games. I can't wait.
I don't believe that you want this. Even really good players don't have a chance against super-advanced NPCs (think how chess grandmasters have barely any chance against modern chess programs running on a fast computer). You will rather get crushed.
What you likely want is NPC that "behave more human-like (or animal-like)" - whatever this means.