Forgive my ignorance, what's going on in this picture?
RPGMemes
Humor, jokes, memes about TTRPGs
Looks like a Microfilm reader?
As for the joke...
It's like the dungeon was so huge they had to "shrink" it to microfilm to be able to fit in "1 page".
I wouldn't say it's a great joke, but that's what I got out of that.
The things in the boxes are microfiche, an archival solution used before scanners were common. The images on them are fingernail-sized and require a bulky device (also pictured) to read.
I work with these things. A fiche is the size of my hand and can hold about 10x23 A4 pages, maybe 10x24 if very dense. Or one ginormous dungeon map, if you really wanted.
"each square is actually 20 feet instead of only 5."
200*
...circa 1984 i drafted a dense full-page dungeon on ⅒-inch graph paper; it was fairly mega-scale...