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

There is a legend. A legend of six heroes destined to protect Equestria from danger. But these six are not the Elements of Harmony. They are more.

The Steadfast Commander.
The True Genius.
The Vigilant Eye.
The Merciless Wrath.
The Fighting Spirit.
The Lone Wolf.

They are the true Protectors of Equestria.
They are the Guardians.
They are Noble.

Alright, so here is the story I have teased on my blog, The Noble Guardians! If you already guessed the concept, good for you! But for the rest of you, this is a Halo: Reach Crossover. I have seen a couple fics in which Six or Jorge are brought to Equestria, but they were always alone, so I decided to bring them all together as one. This will follow the show's storyline, with Noble acting as additional characters to the episodes, but don't worry, I guarantee they will be major characters with their own arcs and there will be plenty of original situations. I will also most likely skip any episodes in which Noble would have little to no involvement. (This will be few and far between, one example being "Call of the Cutie" I mean, even the Mane Six are only minor characters in that episode. I'll probably either mention those in passing or have another story going on with those episodes occurring in the background.) Anyway, see how Noble reacts to becoming Equestria's destined protectors!
Cover image credit goes to Gekko3309.
Naturally, this story contains spoilers for Halo: Reach

Spartans never die, they're just missing in action. This has never been more true for Jorge-052 as, after activating the slipspace drive that was supposed to kill him, he is instead flung into a strange world where war is but a distant memory. Will the aging soldier be able to adapt to this new peaceful planet? Or will his only salvation be found in finding a way back to his own chaotic universe?

(It's my first time, so be gentle)
Now featuring a TVTropes page by Sabo88

When a Necromancer is hurled into the place between places then escapes to another world at the cost of his life it is not the end. Being a Necromancer he returns to life with ease, but is skirting the edges of consciousness, and unable to truly wake as a mysterious figure uses magic to put him on the back of a horse to carry him away into the night.

To make matters worse the phylactery he used to save his own life recreated him as a member of the dominant race with... some errors. His injuries are still present and he's now in a much smaller body with his magic drained to nothingness.

So now he's horribly injured, held captive by an unknown force, in an unfamiliar body, in an unfamiliar world and completely exhausted. He's had worse days. He just can't think of any off the top of his head. So familiar territory then, nothing to worry about.

(Thank you again Tulip for the amazing piece of artwork.)

On Hiatus due to Life. Sorry.

This story is a sequel to The Three Sisters: Extended Family

A story of The Three Sisters Universe

Families are like fudge — mostly sweet with a few nuts. ~ Unknown Author

Chrysalis' daughters are serving their community service in Ponyville. Nothing can go wrong. Right?

Unless they all have their own agenda, and surprises keep piling up, complicating matters further. But anything to broker peace between the Changeling Nation and Equestria... right?

Art by the incomparable Conicer!

Now with a TV Tropes page! Warning: Will Contain spoilers.

In a world ravaged by the living dead, one man has outlasted those with far more strength, speed, and experience. His only advantages are his uncanny luck and peculiar inspiration. This inspiration has never led him astray and even promises a fresh start. All he has to do is build a strange device that follows no earthly science.

While Earth’s story might be over, this cog-jockey’s has just begun.