This game is by Square Enix, right? Being a Final Fantasy fan, I've always been curious about the company's other offshoots. This game sounds like Hitman; I remember my cousin would take down someone, steal their uniform, and then hide the unconscious body somewhere only for it to discovered by a patrol later.
It's not originally by SE, but they publish the more recent games and also own the studio that developed them. It's not quite in the same genre as Hitman. There's less impersonation–though there's more direct combat if you want it and a social aspect where you can talk to people–but it does feel similar in terms of having a lot of opportunities to explore broadly and figure out deep backstories of the characters and places you encounter.
Ah... this was the original multiple paths game... way way way back at the dawn of PC gaming!