Hyperdimension Neptunia belongs to Compile Heart, Idea Factory, Sega and whomever else worked on it.
I really do "What If" scenarios. This was bugging me so I had to write it.
Just... Don't think too hard on any sort of potential plot holes, okay?
Sitting on a chair as she looked out at Planeptune, Neptune sighed softly and yawned before reaching up to rub her eyes. "Darn it, I keep waking up early these days."
"You don't need to be up to watch the sunrise." Histoire reminded her as she floated into the room. "Though I must say, I'm impressed," she gave Neptune a look that was somewhere between admonishing her and praising her, "I would have thought that by now you would have slipped back into your old ways by now."
Neptune shook her head. "It's only been six months, Histy," she gave the small book fairy an amused look. "Give me another six and I'll be back to having you yell at me to do work and stop eating all the pudding again."
Histoire gave Neptune a nod. "I'll hold you to that." She sighed as Neptune looked back out the window. "How are you feeling?"
"I'm fine." Neptune smiled at Histoire. "My back and legs got fixed up good thanks to that alchemist S-Sha knew." She rocked her legs back and forth to prove her point. "I just hope that everything's going..." She trailed off as a portal opened above and in front of her and several bodies fell out of it."
"OOOF!" The older-looking Neptune laughed and rubbed the back of her head as she sat up in the mess of bodies. "Sorry! My calculations were off."
"I'll say." A familiar-looking woman with long, silver hair muttered as she sat up. "Where... Neptune?" She asked, surprise in her voice.
"C-Chrome?" Neptune asked as she pushed herself up and Chrome nodded as Neptune jumped at her, hugging her tightly. "I missed you!"
"It's only been a few months here, right?" Chrome asked as she hugged Neptune back. "I haven't seen you in fifteen years."
"You know..." Another person spoke up. "As heartfelt as all of this is, would you kindly get your fat ass off of me? I don't like being used as a cushion."
"Nep wha?!" Neptune yelped as she jumped off and Chrome stood up before turning and pulling the last person up. "Noire!"
"Jeez!" Noire grumbled and gave the older-looking Neptune a withering glare. "I thought you were kidding when you said Tsunderes make the best landing pad."
"What's going on here?" Another person asked as they walked into the room. "Oh, the other Neptune is back and... What the goodness?!" Everyone looked to see Nepgear staring at the group in surprise, pointing a shaking finger at Noire. "When did Noire dye her hair red?"
"The day I became Black Void." Noire answered back as she crossed her arms under her breasts and rolled her eyes. "Before you ask, Neptune," she looked at the short CPU and gave her the smallest of smiles, "the kids are all CPUs now. Thanks to Croire's help we were able to reform Sharicite in Gamworld, so hopefully things will return to normal."
"But what about the nations?" Neptune asked, concerned.
"Well, Lilac Heart," Chrome began, "didn't need to do much with Planeptune, other than make sure that Trick was never built again. Yellow Heart's ruling over Leanbox and it took almost a decade, but I think things will be more normal there now." She blushed softly, "it's been turned into quite the vacation spot for everyone who's looking to have a week of uninterrupted sexual parties."
Neptune sweat-dropped heavily. "Not sure how I feel about P-Ko becoming the leader of a lewd nation, but she's doing a good job, I hope." Chrome nodded. "That's good. What about Rom and Ram?"
"Pink and Blue Heart are the twin rulers of Lowee." Noire pointed out, "Lowee and Lastation have been working together to fix the environments that went to hell while the Voids were in charge of the nations." A troubled look crossed her face and she sighed. "I've been retired from being a CPU since we reformed Sharicite, my sister's been running the nation as Ebony Heart. She's doing a far better job than I ever did."
"Don't sell yourself short," Chrome pointed out, "the fact that you're the only Void that was worth saving shows that you did a good job anyway."
Noire nodded at her. "The last bits of Fearicite are sealed inside of me and apparently it changed when the world was bathed in Sharicite again, so now I draw upon general fear, not just fear of me."
"So..." Neptune gave her a speculative look. "You aren't going to ruin the world by accident?"
"Oh hell no!" Noire shook her head. "Chrome and I are retired CPUs and we wanted to see this world."
"You wanted to see Neptune again, just admit it." Chrome smirked as Noire blushed and looked away.
"How'd you convince Darksy to help you?" Neptune asked. "I mean, she was explaining stuff to you and Histy before I came home, so..."
"Let me explain it." Croire said from inside the Nepnote. "I can't see the future of a dimension, but whenever I show up, I instantly can see everything that's happened in the dimension, so I knew how to fix what happened with the Sharicite. And don't think I did this because I like CPUs, I owed you a favor, nothing more."
"Didn't you say something about Gamworld being in the Dark Side of Dimensional Space?" Nepgear asked in confusion.
"That dimension's right on the edge." Croire answered her. "That means those CPUs will have to work really hard, but if they don't fuck up royally, they'll have a relatively peaceful world."
"...So where's Filyn?" Neptune asked Chrome.
"She decided to stay in Gamworld, saying she wanted to see it become what it used to be." Chrome answered her. "Though I think she just wants to spend time in Leanbox for some reason."
"Probably to get laid." Noire muttered and Chrome sighed, nodding as she knew that was a possibility. "So..." She gave Neptune a concerned look. "Have you healed since that battle?"
"Yeppers!" Neptune smiled and did a cartwheel to prove her point. "This Nep is fully healed!"
The redheaded Noire smirked at her. "That's good. So, before I forget..." She walked up to Neptune and held out a hand. "I didn't say it before, so I'll say it now. Thank you, for everything, for saving my sister, saving my life and saving my world."
Neptune took her hand and gave it a firm handshake while smiling. "I'd do it all over again in a heartbeat. ...Well, with less tentacles and sword stabs."
Chrome walked over and put her hand on Noire's shoulder, causing the girl to jerk in surprise. "I hope you don't mind us moving in with you then."
Neptune smiled at her. "Not at all."
Histoire looked at them and just shook her head. "Well, I hope you aren't expecting to live here like freeloaders. We have enough of them." Neptune gave her a dirty look while Chrome and Noire both gave her confused looks. A few moments later, she smiled at them. "I'm joking. I welcome both of you to Gamindustri."
They nodded in thanks before Neptune led them off to find them spare rooms, Histoire could only smile happily.
Even if they turned out to be as lazy as Neptune had been, she would never pester them to work.
Because they were the reason Neptune made it home alive from Gamworld.
So yes, Gamworld Noire didn't die due to a big nuclear explosion in this what-if. Thus Gamworld survived and the Candidates went to fix their nations.
I should have mentioned this, but if you were confused by this, go read "Echoes of the Dark" to fully understand and appreciate this chapter.