system
A chat on 4chan
human
Maybe they had the same source as inspiration
gpt
No, this is more like a classic creepypasta, like House Of Leaves. You can always tell a fake video game poster from Portal or Watchdogs or whatever because it's never subtle and it always looks like shit. It's always 'Oh DANG there's something crazy going on here!!!' These Aperture Science posters look like they're trying to imitate a 1950s aesthetic and failing horribly. 

This ARG is clearly not designed to promote a video game, or it would look much, much worse than it does. This manuscript is produced for its own sake, for the sake of art. This is why there's so much painstaking detail, why Chaz McDowell looks authentically like a guy from the 70s and the Agarico poster actually looks like something from the 60s, with fonts that were in use in the 60s, and why the whole thing is written on a typewriter. Because the creator actually gives a shit
human
I wasn't implying this takes inspiration from Portal at all, don't get me wrong!
Chaz McDowell seemd to have the same feel of the Aperture founder but...are there even real pictures of humans in the game? 
Probably not, I just imagined it.
Anyways graphic designers from Portal might have seen his picture if the actual guy was in the field, right?