Technically the supernatural stuff in the early games reacts just like the living. The only difference you can't knock them out. But you can still sneak past them, as any good thief should do. Shadows are your friend. Remember hammer haunts can be killed in one hit with a good backstab. They won't even know you are there if you keep to the shadows. Avoid sleeping zombies, don't get too close they can't even bother you. Keep some holy water on supply if you know you are going into a zombie infested area. Even ghosts can be destroyed using fire arrows IIRC (keep hidden if you are going to snipe them). Water arrows will take out the fire elementals (again snipe from the shadows).
Also you can knock out all living creatures in Thief 1. Burricks will just call nearby enemies as they fall, after being knocked out (make sure you knock them out in the dark so you can sneak away). You can't hide their bodies so it will agitate nearby enemies if they are discovered. Same goes with the mantises/bugmen, easy to knock out, it is a silent knock out, but you can't move their bodies (so try to knock them out in the dark if you can, to make it harder for their bodies to be discovered).
Keep mindful of the surfaces you are walking on, and change your walking speed/sneaking to compensate.
If you have to kill some enemies, remember that sniping from the shadows, when the enemies don't know you are there will do more damage than shooting when they know where you are. Giant spiders come to mind.
There is a possibility that new operating systems, faster computers, and updates like NewDark) has broken some of the sneaking, and increased sound sensitivity of the enemeis in Thief 1. But monsters, and undead should react similarly to all other living as far as sneaking past them. They do not have supernatural night vision.
In Thief 2 you'll encounter human guards and cyborgs with neck protection and large helmets, that can't be knocked out by normal means as well. But sneaking past them works exactly the same. Note: gas arrows are your friend if you want to knock them out. OF course robots, you'll need to use water arrows to take them out silently.
Post edited June 17, 2013 by Baggins