Universes to explore

The Mare Who Once Lived on the Moon In a steampunk reimagining of the universe, Twilight Sparkle finds perhaps the one pony as lonely as she is. It's rather unfortunate that they're on the moon. by MrNumbers 143,130 words · 3,009 · 57
I.D. - That Indestructible Something Gregoria Samson awakens transformed into an Equestrian pony - yet no other human being can perceive her new body in any way. What is the incredible, monumental truth behind her impossible change? by Chatoyance 97,212 words
Oversaturation Too much of a good thing is filling the human universe, and Sunset Shimmer is the only one who can solve the problem before it annihilates her new home. by FanOfMostEverything 36,216 words · 1,081 · 22

Equestria, but not the one you know. Stories that indulge in worldbuilding on an epic scale.

Short story collections

Group Precipitation Stories set in the Oversaturated World, some silly, some less so. by FanOfMostEverything 208,254 words · 564 · 26
Story Shuffle Thirty-one pony one-shots inspired by thirty-one random Magic cards. by FanOfMostEverything 38,899 words · 250 · 7
Verse Averse: Tales of the Versebreakers When musical mayhem threatens Equestria, the brave and misunderstood ponies of the Versebreakers are on the job. Ten music-themed stories by eight talented authors. by horizon 24,898 words · 219 · 3
MLP Time Loops Twilight Sparkle has been here before. In fact, she's been here so often she's thoroughly bored. Time Loop stories for Equestria. by Saphroneth 2,479,751 words · 2,229 · 92