The Fire of Friendship has all but faded. One thousand years ago, Equestria fractured... those who disagreed with Celestia's rule left under the leadership of Princess Luna to found their own nation, their own way of life. Seventy years later, Celestia and Luna both disappeared during the first war, leaving the battered nations leaderless in their absence.

Over the last nine hundred years wars have frequently waged between Equestria and Lunaria, each seeking to unite ponykind under their own ideals. Equestria's mastery of magic often gave it the edge in battle, but never enough for a decisive victory. Peace reigns for now, but recent developments in Lunaria signal a shift in the balance between the two divided nations...

SF (canon species only; no humans) Ponies were magically and genetically engineered to be the perfect servitor race. They are powerful, adaptable, intelligent and completely under the control of their creators. A laboratory accident frees one such pony from her mental chains, but how can one mare save herself and the rest of her kind if she doesn't even know she's a slave?
This is not the Equestria you know and these are not your little ponies... not yet, anyway.

Tags: Adventure, Diamond Dogs, Gryphons, NO HUMANS (did I mention that already?)
Other tags: historical, mind control, Clarke's 3rd Law, excessive use of high energy physics, before they were famous.
Detailed review by PaulAsaran.
Cover art by endrome , used with permission.
Russian translation (partial -- 'unofficially' completed in the comments)
A Soot-Covered World, book 1.

When Sunset Shimmer left Celestia's tutelage, she entered the magic mirror that had shown her dreams coming true, but instead of ending up in a simian mirror-version of Canterlot, she ended up in a strange school of magic, an esoteric, arcane, and clumsy kind of magic, but a potent one nonetheless.

Disoriented, and her mission somewhat derailed, Sunset is nonetheless determined to become an alicorn. She has glimpsed eternity, and will continue to pursue it. Whether the magics of the school of Hogwarts will aid her or not remains to be seen.

Put simply, this is my attempt at making a power fantasy entertaining. Read more about it here.

Thanks to ssokolow for his help with the story.

Sunset struggles against the chains around her. Bound by Princess Celestia's will, her flames, and her degrading morality. Seeking powers to reclaim what was promised, turning away from the ever-watching sun.

Cadance seeks purpose and answers to questions that had been long left unanswered. Entering into a new and unforgiving world. With every pony seeking to use the newest Princess to their end, she must find her path through the shadows and light.

Two sisters begin their cycle anew. The shadows start to dance once more as the darkness swallows the light. Ponies long since thought lost, return. Those shrouded by shade wait with bated breath for their plans to come to fruition. As ancient powers find new hosts, relics lost to the ages beg to resurface.

"Beware pony for you walk the blade's edge between Love and War. Ensure that you do not lose more than you bargained for." -author unknown

"When one peers into a mirror you see your reflection. However upon glimpsing into a broken mirror, you see your heart." -author unknown

"One pony can grow a plant, cast a spell, control a cloud, it is only together that we can change the reality around us." - Princess Celestia

"The light smothers and burns all those that it rejects. Darkness embraces all for it knows that rejection all too well." -author unkown

Sunset Shimmer fled from Equestria in search of the destiny that Celestia sought to deny to her. She dreamed of finding great glory and power in a strange new world. But she emerged on the other side of the mirror in a harsh cruel world beset by demons and troubled by division, conflict and racial animus: the world of Remnant.

Now, years later, Sunset has completed her studies at Canterlot Combat School and is ready to attend Beacon Academy. She hopes that in the more progressive Kingdom of Vale her appearance as a pony faunus will not be held against her the way it was in Atlas, and she can rise as high as her talents permit and seize with both hands the destiny she still yearns for.

Sunset finds herself assigned to lead three fellow freshman at the Huntsman Academy: Jaune Arc, who dreams of becoming a hero elevated above all others; Pyrrha Nikos, a peerless warrior who has everything that Sunset wants and hates everything about it; and Ruby Rose, a simpler and more honest soul who simply wants to save as many people as she can, and who might just light the way to their salvation.

Together they are Team SAPR, and together they are plunged into a world of mysteries, magic, allies and enemies, robot girls and Atlasian black ops experiments. It won't be easy, but if they can work together, teach Jaune how to fight and maybe learn to get along as friends along the way, then they might just save the world.

Original Cover Art by Mix-Up
Current Cover Art by MRK50
Now with a TV Tropes page

Also with a Discord Server