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

One morning, Flash Sentry wakes up in bed next to Sonata Dusk.

Something very clearly happened between them.

But he's not really sure how or why. And he's kind of freaking out.

In a panic, he turns to the one person he thinks can help him...

His ex.

Good plan, right?

(Inspired by the cover art.)

There are 100 billion stars in the Milky Way, and humanity is determined to explore every one. We send probes, probes with the blueprints to reproduce human explorers upon arrival. Uninhabited worlds the galaxy over can be colonized and populated, until after many years they too can join the vast throng of interstellar civilization. But if a probe is very, very lucky, it will land on a populated world instead. Equestria is one such world.

Even so, it's far from perfect for colonization, not with an environment lethal to human life. But each probe is resourceful and armed with the greatest machine intelligence mankind has devised. If placing a human mind into a newly manufactured human body won't work, it will just have to get a little more creative.

This book has a Hardcover! If you want to pick it up, you can grab it here: https://starscribe.net/

This story was written at the behest of Canary In The Coal Mine, who is sponsoring it on my Patreon. As usual, cover by Zutcha. Editing by Two Bit and Sparktail.

Fantastic prereading help from: Chyre, Danger Noodle, Doctor Disco, and Doggyshakespeare (who also did the Esperanto translation). Thank you all for helping to make this story more readable and more consistent for everyone.

A former pink pony finds herself in a new, hostile world and a new friend who's perhaps even more hostile. A small, angry man finds himself with a new friend he didn't want. Can they make it through this new misadventure together, or is it the universe that needs to watch out for them?

Cover art used with permission from Technaro.