Once you finish it, it’s actually really fun watching other people’s playthroughs as well - getting to relive some of the moments vicariously through other people’s eyes is almost as much fun as experiencing them yourself the first time.
It’s also quite amazing just how different each playthrough can be, since the game is so non-linear, people take some crazy paths to get to the end ! It can be frustrating as well when someone just can’t see what is in front of their face though :)
There are also so many subtle elements scattered around that most people miss on their first playthrough, and watching someone else play it really made me appreciate many of the details I missed on my own playthrough and even make connections I didn’t before, and understand aspects of the story that I didn’t fully get the first time.
I think those might actually be frosted glass cups.
Here is the best copy I could find, and the flared edges do not look like plastic cups - also the shiny inside and matte outside looks more like glass frosted on the outside.
PP was not in commercial use until 1957 (not sure when it was first used for cups), PET disposable cups weren’t a thing until the 70s. Disposable cups in the 50s would have been wax paper.