Scare tactic

[Rbman]

im making some sort of a maze, with rooms that have cyberdemons in them but no entrance to these cyberdemons, i only want them there as a scare tactic, but they dont start doing anything till they see you, i tried puting an imp in these rooms to hopefully piss of the cyberdemon but that did nothing, is there a way to make a wall that the cyberdemon can see through but the doom guy cant, and the cyberdemon cant shoot through the wall and hurt the marine?

[Apocalypse]

you could make i tiny hole onder the wall between the room you are in and the room of the cyber demon
and when the player shoots the cyber demon will hear you.

[Dutch Doomer]

Change the areas where the cybers stand in into dummy sectors, at some point when you make noise they will hear you.
That sound you hear when you hit the romero stick is an good scare tactic too and an nice way of exiting an map.

[Javoric]

I don't know what type of level editor you use but if you use doombuilder, go to the things list. Highlight the cyberdemons and set them so that they are deaf. Then, make a wall with a slot for them to see the player through. This way they will only be able to see the player when the player comes near them, not when the player is killing other monsters. The other thing you could do is customize lines between sectors that block sound from other sectors.

[The Ultimate DooMer]

Apocalypse said:

you could make i tiny hole onder the wall between the room you are in and the room of the cyber demon
and when the player shoots the cyber demon will hear you.

And to ensure that the player does shoot before he reaches the cyber, make the first door/switch (preferably at the start room) a shootable one.

[Ezxariarch]

Im not sure what format of doom you are using. If you are using Zdoom-Hexen for Doom format, you can have a line def activate a dormant monsters. Just give your Cyber Demons a tag and have a line with the action "THING_ACTIVATE" activate them.