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

A long time ago, a whole manor, and everypony inside it, mysteriously disappeared without leaving any trace.

But it reappeared at the edge of the Everfree Forest, and Twilight decided to go investigate followed by her friends, only to not come back. Worried, and not wanting to miss an occasion to get their Cutie Masks, the Cutie Mark Crusaders entered the manor at the start of the night, only for two of them to be foalnapped by ghosts, and for the third to barely escape with the help of an old stallion.

Now armed with the Poltergust, a powerful tool to capture ghosts, Apple Bloom returns in the manor, ready to save everypony, even if she has to fight every ghosts in this manor.

A long night of terror starts for her.

Happens between season 2 and season 3. Also possesses some Dark and Drama

The saga now has a TV Tropes page (spoiler for the whole saga).

A very strange phenomenon has recently occurred in the land of Equestria as mysterious portals begin appearing in different locations of the land. But these are no ordinary portals - they are gateways to another world, and serve as a bridge for gigantic creatures to enter and roam Equestria! Including the King of all Monsters: Godzilla!
But how will the Monster King see the ponies and other inhabitants of Equestria? Friends or foes?

A cynical and distrustful man has a drunken conversation at a bar with someone and finds himself waking up in a land of talking ponies the next day. The catch? He's now a Ninetales. "Great...where's the bar?"

Link wakes up in the middle of a field outside of Ponyville. He has no idea of how he got there--last he remembers he was in Hyrule.
But with barely an explanation, he's plunged into a crazy adventure with his newfound friends--an adventure that will save Equestria.

Proofread by Well Geboren

EDIT: Featured October 12th. Forgot to add that till now. XD
Featured AGAIN on November 30th! Woo!

So, my friends and I woke up in this forest none of us recognize, and were scattered by these wooden dog things. Now I gotta find my friends before we get into any more trouble. Now if only I wasn't a foot tall, and can say more than "Eevee"....

This is a random thought that popped into my head one day. I figured I'd get it out now. Still don't quite know where this'll end up, so let's take this adventure together.

Character tags and categories will be added as needed.

Proofread by Zannblade.

Have any theories? Can't remember who is who? Fear not! Thanks to Adenbadens for starting up a Google docs to help with this. You can veiw it here. Beware, wild unmarked spoilers abound in the grass.