3 out of 4 of those can be accomplished in engine at next to no effort. They are artistic changes to add contrast and give a different feeling to the artwork. They haven't drawn in more geometry than the game is outputting, haven't added GI that the game doesn't have, have drawn in shadows that the game doesn't actually render, or anything major, with one possible exception. That's the volumetric light beam, which could have been added in PS and yet not be featured in game.
However the explanation was clear. They touched up the colours and added nothing major. That means tweaking the contrast and saturation, and not drawing wholesale effects into the scene. Thus what we see should be being rendered in game with perhaps a little difference in contrast, less of the vignetting, a change in Helghast light saturation, or other minor adjustments.
If they have drawn in the foggy light without it being in game then there's reason to complain, but at the moment any outrage at what we've seen is totally misplaced.
Avtually that´s what I was thinking of but then why don´t they do the changes in the game, maybe they prefer when the colors are more blend?
The more intense lights on the helmets are probably not in the game unless the orange color is a part of the helmet texture and the foggy light wasn´t in the un-tpuched screenshot.
Anyway I think it look good on both screenshots and I hope they add those extra effects to the full.
This certainly isn't 'smoke and mirrors' to make the game engine look more capable than it really is.
Not at all, I think they can achieve much better graphics than the touched-up screenshot with their Engine.