Just finished playing, got to level 12, ran into a dead end and realised I was playing a demo haha.
This was a great map pack. I enjoyed it and it kept my attention all the way through.
Unless I missed it, the eyes in the wall on an early level, with a lift on each side of the street and the red card behind the opposite door. Was this a secret? If not, it was kind of strange.
I found a few bugs during the playthrough - one is the hole in the crates which is screenshotted above me.
On the first level, the blue key door opens without needing the blue key, as you can see in this shot, it's midway open and I don't have they key in my inventory:
On two levels I managed to get stuck behind some crates:
The hell screenshot / pink floor - the door texture is fixed so it just dissolves as you can see in the shot:
The fences all around this section are non-clipping:
As for the jumping out the train window, I played the arrow version so I never got a chance to see if I would have figured it out, however, having to use arrows is generally the sign of a bad design. I would personally have this damaged or something to make it obvious you can get out.
I never found out how to get to that blue card behind the tv.
I liked the fast opening, automatic, two column doors (around level 10). It's simple but not something I have seen before.
It was a bit clunky with the rooftops on the last map (12?) with the invisible blocking walls. It needs some small walls or something to show that you can't drop off from that side. Then unblock that section because it just ended up with all the lost souls bouncing off the invisible wall and I just stood there on the rooftop and blasted them all without them being able to reach me.
There was another invisible wall which broke immersion for me, it was like an S walkway with small fences. Blue armor on one side, but the other side was some kind of secret I guess? I didn't find it in the end, but for a minute I thought aha I just run and jump off the lift. But I bounced off a blocking wall.
Also the lift into and out of that section - are they intentionally linked? Moving over the one I was talking about kept making the entrance elevator go up and down as well.
Let me know if anything isn't clear and I'll track it down for some better screenshots / details.