This is a fic based on the Time Loop Files, the format of which was first codified by Innortal on fanfiction.net.
Here's a brief guide.
The basic idea is, one character (the Anchor, usually the main character of a fictional setting) is looping back to the very first moments of their parent series every time either they die or some kind of time limit expires. They of course end up monumentally stir crazy given enough time.
Eventually others start to loop as well.
The reset is not always perfect. Sometimes a loop's history will be different to the "prime" loop, or canonical plot.
"Crossover" or "Fusion" loops also occur, randomly. These can involve the home loopers having a guest, or the anchor for one universe spending time in another, or replacements of one character by another.
Vacation Loops are where the Anchor (or others) decide/s "buck it" and lets off steam by doing whatever comes to mind. There's little or no attempt to maintain the original timeline.

In addition, and particularly more recently, it should be known that this story has a collaborative element to it - people may submit loop ideas or loops, ideally at the Spacebattles thread (a link to the current version of which is on the Trope page), and they may become included.

There's two page image options, thanks to Filraen - the current page image has been edited by the original creator from this work of theirs.. The other one is here:
http://hourglass-vectors.deviantart.com/art/MLP-Loops-466030169

When your life is as dull a gray as the world that surrounds you, the mundanities can make it all seem meaningless. Sometimes all we need is a little color -- or six -- to reintroduce us to what truly makes life worth living.

*6-16-2017 Edit, added Rainbow Dash tag because it triggered knighty.*

On the night of the Grand Galloping Gala, Thunderlane couldn't be more annoyed. Dragged to the gala by his CO, he's content to be bitter and moody the whole time. But when he hears a soft melody played by a certain mare, he's intrigued enough to introduce himself to this "Octavia."

She's a nice mare. Sweet and polite, but with what she calls "a roommate complex." Now what could she mean by that?

On the day before her 800th year of her lonely reign without her younger sister, Celestia takes the day before to mourn over her sister ever since she was banished to the moon. But on this particular day of grief, she gets a visit from the Doctor, along with somepony whom she hasn't seen in a very, very long time, her sister Luna.

Any kind of constructive criticism is welcomed. (The key word here is "constructive".)

A special thank you to SecretBrony01 for proofreading this story.

In Equestria's early history, years before Luna had become a princess like her sister, ever before she gotten her cutie mark, she was once plagued with nightmares. She wanted to sleep without these monsters and demons to haunt her. Help does come in a blue box, from a stallion who calls himself "Doctor", with is assistance, and a pony whom everyone thought was Luna's imaginary friend.

Author's note: I do not own any rights to "Doctor Whooves and Assistant" by the fantastic YouTube radio drama series by Ponies with Pockets Productions aka PrierceSmoulder. This story is a tribute to their series that get's better and better with every video.

Also, a huge thank you to SecretBrony01 for editing this.

With the Equestrian Girls movies out, taken place in a universe that everypony from Equestria is in human form, I've decided to do a thought experiment.

The following story has to do with their version of Discord (simply known as Mr. Disc), and what would happen if he had stumbled into the land of Equestria.

A huge thank you to his Highness PrinceCelestia for making the cover art.

Edited by ginger468 and SecretBrony01

This story is a sequel to The Chase

The city of Vanhoover is having the worst winter storm in generations as Mignon Croix has to make his way home from the grocery store. Along the way home, he finds something that will change his life forever, but only if he will take the chance.

Reading The Chase is helpful but not necessary to enjoy this story.

Ditzy doo is crooked. And when a strange creature follows her because of it, she befriends a most unusual pony. (In this story, the Doctor and Ditzy had never met)

Book 3 in my Doctor Whooves series. River, Ditzy, and the Doctor travel back to when chaos ruled Equestria. The three time travelers are assigned a special mission from Celestia and Luna to apprehend Discord. But what happens when the embodiment of chaos takes a liking to Ditzy? There will be chaos, nightmares, and a love that can never be.