Epipelagic/Sunlight Zone: Coal, Wind, & Rain "wake up" in the dream-aquarium without their memories. Basically a tutorial level as they get their bearings & learn the basics about their situation & how this world works. They don't remember their names; so Coal goes by Red, Wind goes by Purple, & Rain goes by Blue. (Red lightheartedly teases him, by calling him Baby Blue.)

  After a bit of mindless bumbling around, awing at the beauty & variety of the exhibits on display, they eventually stumble onto a door with a blank potrait hanging above it. It appears to be the only way forward- they've explored all the other rooms so far- but once they step in, the door behind them shuts tight & locked. The door leading to the room after it doesn't fare much better.

  Trapped, with nowhere else to go, the trio examine the room- it looks like it was once meant to be some sort of classroom, possibly for little kids to watch a video while on a field trip, but all the desks & chairs are overturned, and even the projector seems a little broken. With nothing else to do, they might as well try & restore the classroom to its former glory- but once they're done with that, they all come to a collective realisation: it's not an exact replica, this place is more aquatic-themed, but this is what the layout of their classroom back at school looks like. From the exact number of 30 chairs & tables, the size of the projector, even the shelf in the corner. They remember what their classroom looks like.

  Boths doors to the room- the one leading back, and the one leading forwards opens. When they go back, the portrait is no longer blank, instead depicting the classroom they know from school. That's when the three realise how they can get their memories back- enter the rooms with portraits hanging over their doors & solve whatever puzzles or tasks lay inside.

   They clear more rooms & figure out the basics of who they are pretty quickly- they're classmates, Red & Purple used to date but aren't anymore, what their hobbies & interests are, and so on. The team dynamic is established, and in terms of game mechanics for the hypothetical player: Red has the passive ability of being able to read the caesar ciphers that everything’s written in. When he’s not in the party, you can’t read anything. He’s good at logic puzzles & needs to separate from the party to solve them on his own.

  Purple has the passive ability to jot down all the information & memories the three learn in the aquarium. When she’s not in the party, you can’t check the notebook or save memories (which is required for progress to count). She needs to separate from the party to solve word riddles/item collection. “Blah blah blah insert cryptic description here. Retrieve the thing”

  Blue's passive ability is that he’s the one keeping track of directions so they don’t get lost. When he’s not in the party, the minimap can’t be accessed & you can’t leave whatever room you’re in. He needs to separate from the party to solve dialogue/emotion-based puzzles; mostly talking to the other characters and asking what they might’ve felt and why they felt that way, trying to root out the specific feelings of the memory.

  Basically, because they’re restoring their own memories, their roles are supposed to reflect that. Red restores the order of events, Purple restores what was physically there, Blue restores the emotions. Not everyone is needed to solve every puzzle, but, you know, teamwork's good.

  Mesopelagic/Twilight Zone: Somewhere along the line, Red & Purple start bickering, simply as a result of their clashing personalities. They learn more about their lives & some memories, but the intensity of Red & Purple's arguing keeps increasing, until it builds up into this huge fight between the two; but they stop themselves in the middle of it, when they discover that the aquarium glass starts cracking if someone gets too upset.

  So, y'know, they split up & leave each other alone for a bit to cool off, because they don't wanna risk flooding the building & drowning (haha, they're literally at risk of drowning in their emotions). Meanwhile, Blue is the weird third-wheel child in the middle of his friends' divorce & feels very awkward about it. He tags along with Red, who at first starts Going Off about how Purple's so stuck-up & always scowling even though he's trying to be nice to her, while Blue listens. Then there's a cute bonding moment, where to distract Red & cheer him up, Blue willingly opens up on his own, just a little bit, to talk about the sea-life they're seeing as they walk through one of those aquarium tunnels; signalling to the hypothetical audience that they're in the Twilight Zone, as well as causing Blue & Red to realise that they're getting deeper into the ocean, the more they explore the aquarium.

  Meanwhile, Purple's found & decided to go through a puzzle door on her own. She finds herself on a snowy beach that's somehow raining hail, despite being surrounded by a fake sky that's painted on the walls, leading out to a sea filled with icebergs; where she encounters Sunriver's ghost for the first time. She doesn't remember who the ghost is, but she looks vaguely familiar. The ghost is just floating above the sea beyond the shore. Purple doesn't even feel creeped out, and in her haste to potentially uncover more of her memories, coupled by this... indescribable panging of nostalgia, regret, elation, desperation- she just... starts walking towards the shore. She doesn't stop moving forward, even when she's reached the water, almost as if she's put herself in a trance. Sunriver obviously doesn't want her daughter to drown or give herself hypothermia, so she disappears from sight- not that Purple's aware of that, with her vision almost entirely blocked by the sea & hail at this point.

  Back at the tunnel, Sunriver appears to Red & Blue, but she's unable to speak a word- the dead tell no tales, after all. So, instead, she just tries to mime out what's happening to Red, by pointing him in the direction he has to go, hoping he'll take the hint & follow. Both of them are incredibly creeped out by the ghost, but they do eventually get the hint & go looking for Purple. 

  As they open the door to the beach, Red sees Purple & cries out her actual name, "WINDMARK!" in a panic, but she doesn't hear it, because of the rain. Blue spots a boat they can use, but while Red rushes towards it, Blue just... stays behind on the shore, frozen in his fear & not willing to risk somehow messing up the rescue with his own clumsiness- leaving it all to Red. With Sunriver guiding Red towards Windmark's location, he eventually pulls her out of the sea & onto the boat, snapping her out of the trance. With her daughter safe, Sunriver's ghost disappears once more. Coalfang & Windmark, now remembering theirs & each other's names, almost get into another argument, because now they both remember who Sunriver is, the incident in the past that led to her death, and the fact that they both blame each other for it- but a particularly strong wave snaps them out of it, for long enough to get them to agree they need to row the boat back to shore; returning to the quiet aquarium.

  We're also introduced to new game mechanics- each of the trio can team up to solve puzzles at the same time. 

  Coal & Wind together can solve puzzles where you need to restore a wrecked room to its former glory, reflecting them slowly & quietly repairing their friendship, but also foreshadowing to them repairing their torn memories later on in the story. Coal & Blue… it's something about meeting at each other’s level as equals, because their relationship is initially unbalanced, so it reflects their friendship becoming healthier… sharing information across distances, probably? Information gathering & then coming together to create a full text. Blue & Wind- Same idea of gathering information to create a full picture, but more visual; drawing/taking photos of scattered clues then coming together to create a full image, possibly?

  Coalfang falls into the cracks. He scrabbles at the edges of the room's floor, trying to hold on, but both Wind & Blue just stand there, frozen in horror, until his grip slips. As he's thrown into the darkness, he screams Blue's actual name, "RAINTAIL!" before he's consumed into the darkness below. The quake stops. The lava cools just as quickly as it came. It's an eerie sort of stillness, as the only clue anything had ever changed about the room is the gaping ravine in the middle of the floor. Everything is quiet.

  Wind & Rain quickly get down to business. There's no time for messing around, now. Windmark cannot afford to lose another person- she doesn't like him, but she doesn't want Coalfang to die; and Raintail wants to save his best friend. Wind's still unable to bring herself to look at Sunriver, but she asks Rain to ask her mother if Coalfang's dead- she figures she should know, as a ghost, shouldn't she? Raintail relays the message; Sunriver shakes her head. Coalfang is alive, but he's in danger of losing it if they don't act quickly. Sunriver mimes out taking a deep inhale & holding it. The oxygen is thinner down there due to limited airflow underground; they're gonna have to slow down their breathing & try to remain calm if they don't want to suffocate.

  They find a closet with some climbing gear & oxygen tanks just in case- not that the two teens have any idea how to use them, but they figure Sunriver's going to show them how if they ever need it. Luckily, instead of having to fall down, they find another, more gradual entrance into the caverns, it too opened up by the previous earthquake. Leaving behind the sanitised comforts of an aquarium building, slowly but surely, the two descend into the rocks.

  Abyssal Zone: it's dark, down in the caves, but at least it's not filled with water. There's a bit of a river gently flowing through; it must've caught Coalfang's fall & pushed him elsewhere in the caverns, so Wind & Rain set off, following it. At least they won't get lost in the caves, thanks to the river flowing in one direction. Wind finally brings herself to look at her mother's ghost, but that's only for the fact that Sunriver's ghost glows in the dark, serving as their only light source. The way she talks to the ghost is clinical, stoic. Move here. Go there. It's just a convenient light-source wearing her mother's face. Ignore the way she looks at you with so much sadness in her eyes. Stop it. Raintail treats the ghost with much more sympathy. He can see she just wants to talk to her daughter, and can understand the frustration both of them must feel; but he doesn't speak much, either, not wanting to waste what little air they have down here.

  Eventually, though, Windmark just... can't stand all those pitying looks & sad stares anymore. It's the last straw. Frustrated by everything going on right now, unable to bottle her emotions any longer, she just... breaks down crying on the cavern floor. She doesn't want to- she can't carry on like this. She's so tired of being angry all the time. She's so afraid of losing her- her ex? Friend? Acquaintance, maybe? She's scared. She's confused. She wants her mom back. She just wants to go home.

  Sunriver's ghostly hand is cold & chilling against her cheek. It's not at all the warm, solid presence she remembers, but she looks up, and stares into those empty, white eyes nonetheless. It's not the same. It's exactly the same. It's filled with love & care nonetheless. Her mother doesn't immediately urge her to move on. Instead, they just.. stay there, for a while. Patiently waiting, as Wind's sobs echo through the caverns. But she can't sit here forever, as much as she wants to. Coalfang's life is in their hands. She gets up, dries her tears, and the three move onwards.

  They continue following the river, eventually finding Coalfang lying washed up on the shore of an underground lake. His breathing is laboured, he's shivering in the cold, and he can barely move, but he's alive. They give him more oxygen just in case. Rain initially tries to lift him up to carry him, but due to Rain's eating habits (...or lack thereof), he doesn't have enough strength, so he steps aside again & guiltily lets Wind carry him. The good thing is, they don't have to carry him far. There's light; there's an exit to another part of the aquarium, just on the other side of this cavern.

  When they make it through, Rain notices how freezingly cold it is down here, looks out into the dark lurking just beyond the glass, sees what must be the ocean floor, with a splattering of whalefalls & hydrothermic vents, and he realises they're right at the end of the Abyssal Zone. They're almost done here; they must be. They all decide to stop walking for a bit, stop trying to progress, and just... take a break. They sit Coalfang on a bench, as he recovers under a blanket, his jacket forgone, lost somewhere back at the cave. Just wearing a torn-up shirt with his sleeves exposed, Coal looks more vulnerable than he's ever been. Coal & Wind need time alone if they're going to do this properly; to just... talk, so once again, Raintail has to stand aside. Not putting up a fight, he just nods & goes to wander off by himself, though promises not to go too far. Sunriver also obliges, fading out of sight again.

  The conversation starts off quiet & curt. Polite. Shy. Cautious. How are you? Are you sure you're okay? This situation we're in is crazy, huh? Then it all just escalates & tumbles out. For once, for the first time since they first met when they were 14, they're just being honest with each other. No false bravado, no cold walls, they're just... being people. They both realised they kinda... really messed each other up badly, huh? They're still hurting. They won't- can't ever be lovers again; that bridge was burnt long ago. Neither of them can ever fully forgive each other. But they don't hate each other anymore, either. They missed hanging out. They can be friends. It's a start.

  As the conversation resolves, something appears in each of their hands. They're key-cards, with their respective profiles & names. Not written in any caesar cipher, no, they're in plain English, and they're labelled to open the door to an elevator in the Hadal Zone. This must be their ticket out of here. But their elation at finally having all their memories back, at finally being whole, is cut short- as a scream of despair echoes throughout the corridor.

  They find Raintail, silently exiting another puzzle room he solved on his own. For once, his mask isn't covering his mouth, instead hanging limply around his neck. He's holding a key-card; he's got all his memories, too. Finishing this last room must've done it. But instead of looking relieved at the thought of going home, he just looks... weary. Not exactly apathetic, but full of remorse & regret. See, he really hoped, maybe his utter uselessness & incompetency was just because of his amnesia; but, no. He remembers everything. This is how he's always been; and suddenly he's the most afraid of being perceived & known than he's ever been, and his self-hatred spikes as he now knows the full extent of how he (thinks he's) a useless screw-up that nobody really cares about, and he decides everyone would be better off if he never woke up!