If you consider it "lore" probably Mass Effect or Deltarune. Genuinely not sure which is more sad, but it is what it is.

Mass Effect I read all of the books (yes, including the one where Kai Leng eats Captain Anderson's cereal), read the comics, played through ME1 and ME2 at least 12 times each, went through every single codex entry, and more. Then ME3 came out and completely wiped away any interest I had for good.

Deltarune I know way too much about. Ironically, I don't give a shit about all of the "popular" theories that float around. Despite that I can basically identify where pretty much any dialogue comes from, all the different permutations, all the different hints of backstory, all of it. I used to write a bunch of fics where I was obsessed with making sure I got stuff right, so I'd actually scan over the town map to plan out what I should describe in scenes, or pull dialogue from docs people made of all lines to make sure I got certain character tones right.

Definitely not the best use of my time.