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

It has been almost three years since the Invasion, and the Hive is crumbling. Changelings are dying every day and all attempts to save it have failed. Chrysalis has blamed herself for every lost life, and she has reached the end of her rope. She can't see any way out of this mess, and she's running out of time. There is only one thing she can think of doing to help her changelings, but it costs so much of her. Can she do it?

Coverart by the fantastic Berserkeroo

So what actually happened to the Changeling Queen after the Royal Wedding?
As it turns out, the love blast sent her through the fourth wall, and she spent a year flying through the internet.

Only to land in my head. Sounds great, right? A new, non-imaginary friend that goes anywhere and I can talk to any time about things?
Ha, I wish. Instead I get an insulting pervert who loves to talk back. She says she's making the most of her situation, but it's certainly not all that helpful to me.

I'm sure in for some "fun".

New art by Scarlet Songstress!
I love it so much

Twilight stands in an empty, frozen Canterlot Castle. She's freezing to death, but she dares not move an inch, for fear of failing the test.

When you lose a game, sometimes the only thing you can do is start over...

Twilight stumbles across one of Equestria's most closely-guarded secrets, something that Celestia refuses to tell even her. But how far will she go to find the answers, and will they be worth it in the end?
Meanwhile, Applejack has been having strange nightmares, ones she hasn't experienced since she was a filly. But what do these cryptic sequences mean?
Lastly, Rarity is forced into another conflict with her own element when a disgraced cousin appears, begging for the dressmaker's protection from the law.
But how are these three events connected, and what could it mean for the future -and the past- of Equestria?

Well into the modern age, Researchers, Historians, and Crackpot Theorists alike have remained baffled by the mysterious circumstances surrounding the disappearance of Clover The Clever. Indeed, the only one who could know what happened to that bright unicorn is Clover herself.

(More bittersweet than sad, but close enough)

Nopony was there to help her. She’d taken the shift alone, despite all the rumors. She’d dismissed them as pure nonsense – and now she was to pay for it with her life...

Before the Power Ponies came along, Maretropolis was a second Tartarus, as one ordinary mare is about to discover. But the more you push, sooner or later, something has to give...

It's a typical conclusion for a Wonderbolt's practice session, and for Spitfire, that means getting something a little strange from Soarin. With the help of a fellow Wonderbolt, she tries to learn how to best approach Soarin and ask him the one question on her mind. However, Spitfire is going to need to accomplish this without a major social error if she has any hope of finding out.

Thanks to hawthornbunny, bathroomstahl, and Waterpear for pre-reading/proofreading this story.

Misty Fly dreams of being in the Royal Guard and has the skills to do it, but there's just one problem. She isn't intimidating at all. The Royal Guard tries to remedy this by assigning her to a program run by Iron Will. If she passes, she can become a member of the Royal Guard. Naturally, things don't go exactly as planned.

Takes place 18 months before the pilot episodes.

Thanks to Elusive Element and Frostfur for proofreading this story.

After the events of "Magic Duel", Trixie abandons Ponyville after all the trouble she caused, afraid of what will happen if she were to stay. During her long travel, she stops at a diner to get some food, but this decision will affect Trixie much more than she expects.

Thanks to Midnight Radio Hotline for pre reading this story and for providing editing advice.