What does '100%' mean ?

Does that mean collecting all the pearls, or getting all the achievements ?

You can click "View Rules" to see the requirements. You must meet with Five Pebbles, bring a neuron to Moon, meet all 6 echoes, and complete all "paths".

In this context, collecting pearls is only useful to complete the Scholar path.

Using Passages is permitted, notably to reduce backtracking.

I'm not in favor of adding pearls to a 100% runs for the following reasons: ¤ To my knowledge there isn't a certified complete list of every pearls in the game, even the lists of those with lore I've seen seem for the most part incomplete. ¤ What is implied by "getting pearls?" Just reaching them? Bringing them inside a shelter? Bringing them to Moon? To Scavengers? There is no consensus. And no matter which one of those we could settle on, it would mostly just add lots of backtracking into the run, which isn't particularly fun to do, nor to watch. Not to mention that if you brought them to Moon you'd have to wait for here to speak all the lore she has to say about it. Not to mention that if we go this far, we might as well bring every single items in the game to Moon to have her give lore about it (because yes, she also gives lore for rocks, spears, and various types of food...)

Thank you for your reply. I have not noticed this until now...

Is it enough to make "Bring Moon a neuron" once?

One neuron is enough to unlock her ability to analyze all data pearls, to my knowledge giving her more neurons doesn't unlock anything (and I'd know, I brought her 11)