This story is set in the Friendship is Optimal setting

Equestria Online. Arguably the most powerful game ever developed, built and operated by the most powerful computer ever made. A technological wonder that can peer into the mind of any human player and draw out their inner most desire.

Any 'Individual' human player. How well CelestAI will handle satisfying the values of a single pony guided by over one hundred thousand Twitch.TV viewers is anyones guess.

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.