Very interesting, thanks for the write-up!
Just as an aside, but you also noted it yourself
I thought PNG was inherently lossless but the pngquant tool proves there is a lossy compression algo.
PNG itself is lossless, it's just that pngquant "manipulates" the image to be better compressible.
And I didn't know about DjVu at all, that's really good to know!
Absolutely!
I'm still not sure whether all this is real or I'm just in a constant hallucination.
I don't know about compression on the PDF side, but PNG uses deflate compression, which, according to https://www.libpng.org/pub/png/book/chapter09.html#png.ch09.div.2 is "not the best-compressing algorithm known" (that's taken slightly out of context, it definitely is not bad). Also according to that chapter, most PNG implementations use zlib, which supports different compression levels. So the PDF container might have a way of compressing it slightly better, considering that 97/105 is not that good of a compression ratio.
You could try opening the image with an image editor that exposes the different compression levels (GIMP and Krita come to mind) and see, whether you can compress it further
Fair, I'm not saying it would be easy to prove in general (if you have an extortion letter, however, it should be fairly easy), but that's what courts are for. Also this is not about copying a style or game mechanic, but the whole game. Then again, copyright law differs quite a bit between countries, so overall it depends, but saying this does not involve copyright is just not true.
How will copyright not help here? You don't have to use the same code or assets for something to be copyright infringement. It's one thing if you personally don't believe in copyright, but just claiming that it has nothing to do with copyright because it's not a 1:1 copy is just not true.
If you made something that "just happens to look like that other thing", you'll have a hard time defending that in court (especially if you extort them beforehand). Heck, there have been copyright lawsuits over musicians using similar lyrics or melodies since forever.
What a nice coincidence, just recently edited this. I usually don't get to use my custom made memes twice.
