Okay so uh
I DID IT

1 year, 8 months and 17 days after the game's release, I've 100%ed Spelunky 2!, by which I mean I have collected every achievement. Most of the last year was spent on just finding the last item—

And this was without ANY consultation of faqs, guides or spoilers! Me and Miguel from Spooky Squid games did coop runs and shared information between ourselves, but no information came in from outside unless accidental (and I can count the significant accidental leaks on one finger)

I can't move to the Fediverse properly until I reproduce my famous pinned post from the birdsite, so here it is:

P.S.A. To all vintage computer and video game collectors:

Go through your collections and GET THE DAMN BATTERIES OUT!

Now! Don't wait! Seriously, put down the phone, go to your collection and take out all the batteries. Right now! Even if they look "okay" they are NOT SAFE after this much time.