This is thrilling and intriguing! Exactly the kind of story I've been wanting to read or write! I look forward to a widening view of this world!

An interesting start, though typically, numbers should be written as words, not numbers, so maybe consider "Third Memory" for the title? Small things like that just make something look a tad more professional.
[Someone sighed, "Sarah…"] As you're telling it from Sarah's POV, even in the third person, maybe use the name there rather than just someone, as Sarah knows who it is.
Sarah seems quite solid throughout, until [The girl curled herself back up into ball and started to rock again.] She seems to speak about the whole thing quite casually, candidly, not like something that's going to make her curl into a ball. Maybe consider building that bit up more, or having her remain more solid.
I don't think you need the italics to emphasise things here. Leave it up to the reader to decide where the emphasis lies; otherwise it might jar with them.
["The End of the World."] I don't think you need to have the capitals there; it'd be powerful enough without them, and with them, it doesn't read quite right.
Hope that helps.

Captivating. This single word can describe this chapter. My only qualm is that I don't know more. You've seriously dropped me into the end of the world with nothing more than the small prediction of the prologue. I would never had expected this leaving the first chapter.

First things first. The hooks for this chapter is non existent. Rather this entire chapter is a hook. With very little build up, you've successfully piqued my interest. However this could end up being a double edged sword. I applaud you for foregoing the traditional build up chapters and just tossing the readers into the thick of it. I have to say though that most of the time these just don't work for me. Very good job making it successful.

The main character seems likable to me. Her reaction to the sudden change and the unknown is pretty spot on. I'm pretty sure I'd be just as disorientated and distressed. I'm also sure I'd have done the same thing that Leto did if I were in his position. Easily related to characters are the best way to start a story in my opinion.

The imagery that your language brings is a huge boon. As I have said and continue to say. It makes it a joy to read.

This sentence:

[Her stomach heaved and she lurched, ejecting a small puddle of blood and bile onto the ground as she coughed, hacked and retched.]

You may want to consider chopping it down to two or three sentences and removing the multiple synonyms for coughing.

[Her stomach heaved and lurched. A small puddle of blood and bile spilled onto the ground as she fell into a retching fit.]

Overall, it's a great story and I'm interested in see where it takes me.

Definitely an interesting prologue. Nice and short, and gives a decent peek into the world (in this case what may or may not be going through the character's head). It's enough for me to keep reading and therefore it does its job exceptionally well. I have a feeling I'll be looking forward to this story.

To start off, it seems to me that Sarah has a problem with counselors. She seems like a sound individual that weird things are happening to. So far I like her just and for a first chapter that's vital.

The language you use is what I've come to expect from your work. Both vivid and fluid your words are also fairly simplistic and easy to read. Personally this is an underrated talent in this generation of writers. Plenty of people are too concerned with emulating writers who are more purple.

I also love the way you depict her meticulous nature. I think you made a good decision to write it into the prologue this way. I'll have to tell you though that perhaps tone it back a bit if plan to keep it as a sort of theme. It may end up being too intrusive if you don't.

It wouldn't be a review by Nox (me) if I didn't comment on the beginning and end hooks (which the end one pretty strong). While opening with the "tick tick tick" is interesting. I feel as though it's a weak way to keep the reader interested. The ending however is a different story. I'm not sure how you're going to tie that into the story, but I want to advise you to make sure you have a decent explanation of why she sees these things. I'm pretty quick to suspend my "bubble of belief", but others not so much. I know some people will drop your work if your reason doesn't satisfy them. That being said, I think you made it into a good bait for the reader. I didn't expect the end of the world to factor into the work. It has piqued my interest for sure.

This is good, really good. Your language is rich, your pacing steady and you describe neither too little nor too much. Your character feel real and they're interesting. And of course, your story concept is great!

I'm curious, how exactly did the Earth stop spinning? I mean, does it show the same side to the Sun always (which would mean that it either still spins, though slowly, or it also stopped circling the Sun) or does the "land of Eternal Twilight" move slowly as the planet still circles around the sun?

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"The silent reply made her skin crawl." - I'd question this sentence. If her reply was nothing but silence, then you shouldn't say "the silent reply", because that gives the impression that there is a reply, but it's whispered or something.

Missing commas:

"What not even a thank you?"

"That's why we're out here isn't it?"

"It needs new parts alright." Not 100% sure about this, but I'd put a comma before "alright"...

"While they're distracted you can go gather food." - I'm not sure about this one either, I was never good with grammar theory, and it might be different in English than in Finnish, but my instinct tells me there should be a comma between the sentences.

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All in all, a very interesting beginning of a story. I expected much, and the only thing I was disappointed in was the length, lol.

Nice subtle description of character appearances in the beginning. Also, the counting is a great way to imply the passage of time. The scarcity of description in between the dialogue doesn't bother me at all, you brought the scene very alive in my mind.

Hmm... My music for this story is probably The Pretty Reckless, many of their songs feel suitable.

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And now for a little nit-picking:

"Eight hundred and eighty-one, shecounted-" - One of those disappearing spaces again. -.-'

"She said that did she?" - Missing a comma there.

This is amazing.
Your language is brilliant and instantly engaging. Wish I could write like this :)

Continue! :)
xxx

This is really interesting.
I will defo keep on reading! :)

Also Could you check out my story 'Fall for monsters' please.
I'd be really grateful
any way I love your idea :)
keep writing
x