I’m not sure if the broken wall works inside. Its more for outside walls, but try it anyway. Doing that is good practice with brushes.
It could happen. Maybe if he makes the rest of the environment look suitably destroyed. It could just simply be a wall that wore down/collapsed on its own.
Went back to basics with the lighting in the hallway.
When I learned about spotlight effects and such I sorta got carried away… 
Thanks for your help, Ibanez. I’ll see if I can implement some of those ideas. I’ll also work on consistency in my map, making everything look equally worn and destroyed.
You’re welcome. And before you go any further with what you have there, lower the intensity of those lights and bring them down away from the ceiling, so there isn’t a huge painful white spot directly around the light itself. 
Stick some decal doors along that hallway so it looks like there are inaccessible rooms, or even make some that you can open up and enter.
Alright, fixed the lights in the first room and softened all of the dome lights.
Alright, I think I’m gonna call it a night. First, though, what do you think of the color of the lights? I have it a very light shade of yellow, is it too subtle?
EDIT:
Deal. I was also going to put some pipe props or something along the wall to make it more interesting.
Looks great.
Some pipes would add some detail too.
Maybe add a ragdoll at the end of the blood stain.
Have a few lights that aren’t working, to five it a run down feel (Or even flickering)
Think about this logically; would the ceiling above the broken wall be the same texture as the rest of the ceiling?
There really isn’t a reason for the hole, but if you want it there, I would recommend making a hole in the ceiling as if something fell through.
That room’s on a basement level. But I see what you mean. I was doing it just to do it as suggested by Ibanez and you.
Basically, when you add something, think Why is this here? If you can’t think of a reason, don’t put it in.
You should add damage to the ceiling, and add blast mark decals, also I don’t think walls break like that with sharp corners.
Making a door frame would greatly improve the looks of that room, IMO.
Looking better and better. The lighting feels a little yellow to me, but that just may be me.
I did yellow it up a bit, but I think I’ll back it off a tad. I wanted it to look softer, not all jaundiced up.