Just wanted to report that the fix works for the most part.
From what I've tested the levels where it work are the Main menu, Asylum Aftermath, Deadly Cargo, Hunter and Hunted, and Traditions of the trade.
The effect still seems to be broken on The Wang Fou Incident (Fog below streetlamps pause at certain angles) and Beldingford Manor (Start of level drain water - Lake - Window rain pauses at certain angles).
Any chance you would be able to patch the .exe further so these levels work, or have you already done all that can be done?
Not sure if it matters, but I've provided the Steam .exe in case that's the reason those levels don't work with my version?
Did you just do a simple hexedit or did you decompile the .exe? Perhaps you could provide the info of what was changed and how you did it? (If not too complicated)
After some digging I found that the GOG version was used for the fix EXE.
I was then able to easily compare the files to find that the hex string (correct term?)
53 6A 18 53 50 FF 92 FC 00 00 00
was replaced with
90 90 90 90 90 90 90 90 90 90 90.
I was easily able to find and replace the same instance in the Steam EXE.
The issues I stated above are still present.
After further testing it DOES partially work at Beldingford Manor. The sky and (partial) fog over the lake move.