When the map changes to the outside area, if you noclip back the way you came, the lobby is now empty (and VERY shiny) and the plaque has moved closer to the entrance.
The disappearance of the signs in the next chapter makes sense, thereās no point in including extra assets if them if you canāt see them. One thing I found weird though was for the first cipher found. If I went through the load to the next chapter, and then came back, that room was completely empty. All the stuff in there just disappeared. I had to reload the map from a save/through the chapter selection to get it to show up again. Probably just a bug though.
I completely agree with you on this. While I think I may have made decent progress on the tic-tac-toe code, that fact that itās outside QE makes me think itās completely irrelevant, even if it turns out to be solvable at some point. And youāre right again that the overlay code is clearly lacking anything telling us what code it is. I keep meaning to go check out that area more thoroughly.
Maybe some objects there are arranged in the shape of a letter or something.
Unless its purposely designed to NOT show that its code B. The number code could turn out to be code D, in which case the overlay HAS to be B as it would be the only one weāre missing.
The whiteboard thatās in the anomalous materials chapter (the one with the tic-tac-toe code) is also in the QE chapter. Itās behind a locked door in AM, INCORRECT: ābut freely available in QE, so Iām willing to bet it is relevant.ā
Edit: Nevermind Iām an idiot. I know I saw that same board somewhere else because I have the distinct memory of thinking āhmmm, thatās the same board as was in AM.ā I thought it was in QE, but I just made another pass through there and canāt find it anywhere.
Just uploaded all the whiteboards and various bits of scrawl that I could find from looking through the texture files - annoyingly I didnāt spot the decals for our code B whilst looking throughā¦ and there are one hell of a lot to look through - if I feel brave Iāll dip in for a second run
Itās locked in AM, but you can get in there after the Resonance Cascade, the guard can shoot the windows and you can jump right in. Also, irrelevantā¦ but in there is this weird little machine where if you hit the button the arm changes position. I havenāt noticed it elsewhere yet.
Ah, very good, I was hoping someone would do this as I do not know how.
Oh, goodie. Iāll take a good long look at those.
Edit: Mouse, what machine is that? I looked all over for interactive lab things but never found any.
To look yourself then the easiest way is to look using the texture viewer within the hammer editor (part of source sdk), then once I found interesting files to look at I used a third party program called VTFedit to open them at native resolution, then a quick image capture from there.
I havent checked the ones Iāve uploaded yet, but Iād urge a second person to have a looksy in hammer in case thereās something they pick up on that I donāt - also has anyone else checked the sound files yet for further coded beeps? 
NB: filenames Iāve used are same as within the game
I get off soon, and iāll poke around. I want to decompile a few of the maps and poke around there too.
Not sure if this is of any use.
You can find these two hatches at the end of Lambda complex, in the āshotgun scientistā room
Okay, Iāve been looking at those whiteboards. Some of it did stick out, but almost all of that was stuff weāve already found.
One thing I did notice is that Dr. Horn specifically requests that that one whiteboard not be wiped, but itās probably nothing, and I canāt make heads nor tails of anything on that boardā¦
The second is that there a lot of references to optronics all over the boards.
Thatās not the only board he requests not to wipe, so I doubt itās anything special. There is also https://imageshack.us/photo/my-images/59/c2a4xlabboard2.jpg/. It might be worth noting that theyāre both found in the same room, though. I think theyāre both found in the room with the tao cannon, but Iām not positive.
Guys, your all forgetting something. Once we get all four codes, we have no idea what to do with them!
Also, has anyone seen Dr. Stones office? hes listed on the plaque, but i cant find any reference to him anywhere else.
https://steamcommunity.com/sharedfiles/filedetails/?id=97211804
I assume the codes help convert the message into something,
Maybe Dr. Stones left/was killed in a horrible accident.
Pretty sure thereās nothing new on those whiteboards now Iāve had a look, some of the alien descriptions were quite nice to read though.
I couldnāt find any trace of the red/yellow/green symbols from Code B while looking through the texture files but then I think itās pretty easy to set one image file to be viewed in the editor which is then altered for in-game viewing - if thatās the case then it could similarly be there are other images hidden - oh well 
And yes, typically there will be a cipher text (most likely the long string of numbers from Dr Horn to Dr Bottomley) and then a key or keys which are used to decrypt themā¦
At a guess weāre going at some stage end up with translating those numbers into another set of numbers 1-127 which can then be directly converted into their corresponding ASCII symbols and give us something legible. It might even simply end up with the numbers 1-26 for a direct a-z substitution
I thought I was onto something when I tied the three codes we have so far into the RSA encryption earlier, but even on the RSA wiki page it says itās usual to have another layer of encryption before this - which might be unveiled by the final codeā¦ or I might have been barking up the wrong tree completely.
I didnāt find this, but someone found The Pizza Is A LIE at the very start of Anomalous Materials:
https://www.youtube.com/watch?v=hq93m0nJ7xw
EDIT: And a legit way to access one in Surface Tension:
https://www.youtube.com/watch?v=L3cdUQv5h6Q
EDIT2: And another one in Black Mesa Inbound!
The model is called qe_canvaspainting with 3 skins
found a big CM in a room on itās own - mapper signature maybe
https://picasaweb.google.com/HughJundys/BlackMesa#5789988009286777282
random pics here:
Dr. Stone has no office and no picture, Dr. Foreman has a cool mohawk though