Talks broke down. The unification failed. Hearth's Warming have never occurred. The Great Pony War divided the land, and fears of a prophecy forced the unicorns deep underground and into near extinction.

Almost one thousand years have passed. The curious unicorn Sparkle yearns to breach the surface to discover its many wonders and to search for her missing father and brother, both of whom crossed over many years ago. She is forbidden to leave the safety of her subterranean village of Unicornia until she discovers an orange earth pony washed up on the shores of an underground river. That pony bears one of the six Elements fabled to change the world.

Or destroy it.

Cover art credit goes to ouyrof.

Re:Harmony was conceived before Season 4 aired, so some personalities and character relations do not line up with the show's canon.

Also, please refrain from revealing spoilers in the comments. Thanks!