Thanks for the feedback! I'm relatively new to game development, so I don't know how to make smart NPCs. I did it like this: each NPC has a variable that represents honesty. At first, the honesty % is high, but it can go down or up depending on your relationship with them. You can use different strategies. If both of them give you the same numbers, someone is lying. Or if someone names your number, they're also lying. You have to figure out the password by the method of elimination.