For a while I really wanted to make a immersive sim. made in unreal engine and blender. I think the game systems and the levels were coming along but making humanoid models was too much difficulty and I gave up.
In this video the player sneaks around, opens physics doors, carries a object, and rides an elevator.
NPC interactions are one of the parts I found most fun as a kid in games and I am always chasing that high. Here in this video I trained an NPC to navigate through obstacles and open and close doors.
In this video a guard is on patrol. He will open doors and ride elevators to patrol his route. If there emergent objectives like turning lights back on he will do those too.