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

The following transcripts are of a journal found in Ponyville on April 16th of this year. The last recorded contact with the town had been 3 days prior, on the 13th, when a team under orders from Princess Celestia was sent to look into several missing pony reports in the area. When another group of investigators were sent on the 16th, the town was found deserted. The journal’s owner is believed to be the princess’s personal student, Twilight Sparkle. None of the town’s inhabitants have been located in the weeks since.

Readings:
Nimbus Productions
Scribbler Productions

I highly recommend both of them.

A print version of all the stories in this series can be found here. (There is currently a printing error I am working to correct. This will be available again soon.)

This story is a sequel to A FLEet|ng LIght |n thE DArknEsS

Case Report: Summary of Events
Submitted by: Verdant Vines
Location: Ponyville
Date(s): April 16th to April 23rd
Case: Ponyville Mass Disappearance (#3467)
Classification: Top Secret

To whom it may concern,

What follows is an update on the status of the investigation into the disappearance of the entire citizenship of Ponyville.

Readings:
Nimbus Productions - First Chapter
Scribbler Productions - Full Story

I highly recommend both of them.

A print version of all the stories in this series can be found here. (There is currently a printing error I am working to correct. This will be available again soon.)

This story is a sequel to A Glimmer of Hope in the Black

Declaration from White Clover
Date(s): April 26th
Relevant Case: Ponyville Mass Disappearance (#3467)
Classification: Top Secret

To whom it may concern,

As of this declaration, all those stationed in the town of Ponyville tasked with investigating the citizenship’s disappearance are to begin immediate psychological evaluations. If the results of an individual’s evaluation is considered troubling, a mandatory period of rest and recovery will be required before they may resume duty on any case.

Special thanks to Petrichord, Solocitizen, Garnot, Floydien, and Door Belle for their help with the writing, editing or proofreading of this story.

A print version of all the stories in this series can be found here. (There is currently a printing error I am working to correct. This will be available again soon.)

This story is a sequel to Pray, Hope and Wander

Case Report: Update - May 2nd
Submitted by: Verdant Vines
Location: Ponyville
Date: May 2nd
Case: Ponyville Mass Disappearance (#3467)
Classification: Top Secret

White Clover,

Given the new writings included in the addendum to the provided journal transcription, I’ve elected to continue our investigation through conversing with whoever, or whatever, is on the other side of it. They claim to be Twilight Sparkle, Princess Celestia's personal student. I’d like to request that Princess Celestia is not informed of this possibility until we can verify their identity.

As such, from this day forward I will be sending daily reports before sundown with transcription of our conversations, along with any thoughts I have. Included with these documents is a formal request of personnel transfer for Doctor Blue Sky to my team in order to assist with any psychological evaluations related to the writer of the journal. His team will continue to support evaluations of personnel working the case.

Special thanks to FloydienSlip, Petrichord, and KorenCZ11 for their help with feedback.

A print version of all the stories in this series can be found here. (There is currently a printing error I am working to correct. This will be available again soon.)

Idol Hooves holds a special place in Equestria. He's probably the only exiled changeling to serve in the Royal Guard, or at least, that's what he expects, as exiles don't really broadcast that fact. However, it's well known that Princess Celestia loves all of her little ponies, and her guards perhaps more so, and that makes it one of the best ways for a changeling to discreetly feed.

But how does a changeling even get there, let alone get exiled in the first place? For that matter, why would it ever go to Canterlot? Set a number of years before the series proper, before Luna’s redemption, Idol details how he was exiled, the ponies he’s met, and the series of misadventures that led him to joining the Royal Guard, and should continue a good ways into the series, as something of an alternate perspective.

Soon, he’ll have to deal with a boisterous new princess to serve and a royal wedding in the works bringing a third to power. Will his old instincts bring this new life crashing down around him? What precipitates Chrysalis’s ill-fated assault on Canterlot? Is it really so wrong for a changeling to enjoy good craftsmanship to an obsessive degree?

New cover art provided by the fantastic Carnifex

And a TVTropes page here.

And an Ask Blog of questionable canonity!
Out of Idol Curiosity

Fanart by Norad2! Major thanks! Short For a Royal Guard

Art by Egophiliac of Idol and his Daring Duckie Please don't tell him what that brush is meant for.

Rating updated to (T), it's a bit darker than (E)
Comedy Tag added as well
And changed the character tags a bit.