Sequel: Left Behind: Sunny Disposition
Apparently it was scouted and is on EqD too

Nightmare Moon was meant to be released after a thousand years. A momentous occasion for her but terrifying for all the ponies on her day of freedom. She would get revenge on her sister and cover the world in darkness and shape everything to fit it.

That was the plan, at least. Instead, something went awry with the spell and she wasn't released when she was supposed to be. The mare-in-the-moon is brought into a world with stagnated technology, giant cities, and no sign of her sister or any of the other immortals. In fact, ponies don't seem terrified of her at all, and the stay within the core of her powers infused and changed the alicorn's body drastically.

The alicorn had no obstacles left! But...she was also a relic of the past. A past everyone seemed to have forgotten. A past she could no longer look upon.

Artwork by ElkaArt. Link in source.
Big thanks to Kryostase for helping spot errors I've missed.

After a tragic accident, a human ends up in Lord Tirek's body, as part of an attempt to reform the villain after his recent escapades. While the hero of our tale is trying to make sense of his new surroundings, the rest of Equestria thinks that the most terrible threat that their world has ever seen is back...
And the powers that be are definitely not happy about it.
New Cover Art By Shadow Bolt

Fluttershy is a normal pony living a normal life. Sure, saving the world once is an achievement, but other than that she was content with the life she has.

But when she finds two abandoned changeling nymphs, her life is quickly turned upside down. Now she cares for young two creatures she knows nothing about, and they don’t seem to trust her.

She is determined to give them the best life that she can.

Edit (Aug. 8th, 2021):

TN, OP now has an editor! Thank you to Helping Hoof for helping me with my work.

Effective communication is important in any friendship.

Unfortunately for Twilight, Tempest Shadow and Pharynx communicate almost exclusively in overwhelming force.

Having your housemate call the plumber is pretty normal.

Having a changeling show up as the plumber is significantly less normal.

Inspired by Admiral Biscuit's writing challenge.

This story is a sequel to That Changeling's a Pony!

Like most ponies, Maxilla the exiled changeling doesn’t believe that Daring Do is real. However, fate seems determined to prove her wrong in the most dramatic way possible.

After all, it isn’t every day that a changeling gets dragged along on an adventure and subsequently immortalised in Daring Do literature and merchandise.

This story is a sequel to That Changeling's a Pony!

Maxilla is an exiled changeling who resides in Baltimare and writes stories for a living. Life’s pretty normal and pony-like for her, until she’s visited by a very unusual fan who just won’t leave her alone.

Like ponies, changelings can get pretty paranoid at times. After all, it's not every day that a changeling gets kicked out of the hive for being a pony.

The Mane Seven explore a distant island several miles off the coast of Equestria. What they see fills their hearts with dread. How can this be? How can there be a land so silent? So empty?

Coriander Cumin and his daughter, Saffron Masala, are struggling with their restaurant. Business had been good and the reviews had been good, all except for one.

Esteemed food critic, Last Word, gave their restaurant a very scathing review. It was a crushing blow to their image as mob mentality settled in and less ponies frequented the establishment.

They need help keeping it open, so they turn to the only stallion they can think of that could be of any assistance, Tirek's Kitchen owner, Gordon Ramsay.

Will he be able to help them or is it a lost cause? Read and find out.