Inspired by the heroics of the mysterious mare known as the Stable Dweller, Silver Storm, a guard of the town of Marefort, decides to go on a daring mission to rescue her captured brother. Of course things rarely go as planned and her attempts at heroism drags her into a tangled web of plots and conspiracies as warring factions vie for control over the last great city: Dise.

Spanish Version translated by Spaniard-Kiwi: https://www.deviantart.com/spaniard-kiwi/art/Fallout-Ecuestria-Heroes-996263393

It is the year 2038, and the Earth is slowly being consumed by a space-borne monstrosity dubbed the Black Tide, which is using nanotechnology to remake the planet into something hideously alien.

Erin Olsen works for Project Harmonics, humanity's last-ditch effort to find a new world before the Tide can wipe them out. But when that world is found, and it turns out to be occupied, Erin will need to find the courage to face the unknown in order to save the inhabitants of both worlds.

(Many thanks to Easteu for the fantastic cover image for this story!)

Now with its own TV Tropes page

There is now a follow-up to this story: Sunflower - Side Projects
Sequel: Project Sunflower: Harmony