Earlier today I posted a blog with some of my old ideas (totally not shameless plug). Here's yet another one that's basically copy+pasted, free for anyone to use if they so choose:

Building Equestria Universe:
This would be (as previously planned) two separate stories that exist in the same universe, though not direct sequels. The history of Equestria is left mostly unexplored in canon and it leaves for awesome fanfic opportunity. The first story:
Building Equestria:
Sometime after the imprisonment of Discord, ponies start to call for some sort of unification. Many of the tribes meet, (think Princess Platinum, or a descendant of hers). After some talks, it seems clear that everyone wants to rule. The two sisters of the everfree are believed to be the rightful rulers by many of the common ponies. The story would build upon Celestia dealing with day to day life, building good will among ponies, dealing with politics, and in some cases amassing an army. Luna would form the Lunar guard, a task force of elite knights that would turn the tides of war from the shadows. It would take some inspiration from game of thrones, a dark magic priestess would lure Luna into the ways of dark magic. Her first stepping stone would be watching one of her trusted knights lose a duel (in a minor politics game) because his enemy dishonorable cheated (throwing sand in his eye or something akin to that). Instead of ending the duel (first to draw blood) there, the other knight would saw off luna's knights horn with his sword. Luna challenges the knight out of anger but is denied. She later sees him and forces him into a duel (they are in political talks and are not allowed to fight with duel rights). The stallion is unfazed, smirking and cocky as ever he accepts. They fight, he tries that dirty trick on her and her anger spews forth. They are entrapped in a sphere of darkness, screams can be vaguely heard from the outside, as if the fighting was far away. When the sphere dissipates, there is nothing left but a few bloody stains and remnants of the stallions armor. This also leads to the first split between Celestia and Luna. The knight has not been found and the prince of their castle blames Luna, who was in a rage yesterday. Luna denies it, having her knights clean the scene and dispose of any evidence that there was. Celestia uses the prince's lack of evidence against him, but in private tells Luna that she 'has a good idea what happened to the knight'. Over the course of the story, Celestia would gain fame, but since Luna works in the shadows her work would go unnoticed. Luna would eventually slay the priestess, who are pretty vile, fulfilling their prophecy of NMM though to their unexpected deaths (unexpected to them, at least).
The last story arc would have them succeeding in the unification of Equestria and things seem to be winding down, a few years time leap. Luna is not in the spotlight, though she holds NMM in her she finds comfort in her Lunar guard. Sombra would come up on the radar, amassing an army and keeping ponies as slaves. Luna and her guard are sent in first to assassinate Sombra, while Celestia would march on with a small army (~200) as most of their forces are either needed to protect Equestria or retired (Note that at their peak in the story, the army would have about 5000, population of ponies is smaller). The plan utterly fails as most of Luna's taskforce dies or is seriously injured. Celestia arrives just in time. With the home turf advantage sombra gets the better of them, knocking out Celestia and forcing NMM's power from Luna. When Celestia wakes the crystal empire is fading and all surviving units are set to retreat. Luna is only able to recover a fraction of her task force, unable to even get the remains of those that died. Luna would give her speech from the show (slightly altered to reflect that her ponies died and will receive no recognition from the world they help built), story ends as she is about to fight Celestia.
Dream Walkers:
The second story in the universe, probably the least detailed of all of these ideas, would feature the Dream Guard. Set about ~250 years after Luna's banishment, the Dream Guard is a unit that is basically a joke among many of the public and the military. Celestia established the Dream Guard not too long after Luna's banishment. She hoped to tap into the magic that Luna possessed to achieve a link. The story would follow a paralyzed pegasus (the wings are paralyzed) who as a foal would use dreaming to act out flight. The pegasus would become so enamored with dreams that they would eventually join the Dream Guard, only to realize that they are seen as a joke, called in to help simple ailments. The Captain of the Guard itself accepts the pegasus, who shows potential despite not being a unicorn. The field of dream magic has only slowly opened up despite the time since establishment. The Captain himself can only pull a few ponies into a dream if they're sitting next to him. However the Captain believes they're on the precipice of a discovery in dream magic. A plane of dreams, in which they could be used to travel through dreams from 'across the town, maybe even the country'. They are eventually able to do so, the pegasus' ability to fly in dreams lets them walk into the plane with relative ease (though exiting a dream is much harder for the pegasus). In one scenario that would lead to more respect among the Dream Guard, a dragon would be sleeping cause smog and local fires. Some of the guard wish to attack it, but the dream guard is able to use the diplomatic approach. Eventually the guard would try to contact Luna. The pegasus would refuse to give up, eventually leaving NMM free on the dream plane. NMM is able to induce mass hysteria and mentally influence ponies. Cults begin to arise, (in order to give the story more meat, it might follow a Solar Guard in times like these). And then eventually the dream guard is able to beat NMM in the dream plane, eventually sealing it off once again. Celestia would thank them for their efforts but disbands the Dream Guard realizing the dangers it possesses.
Like I said, this one is not as well thought out as the others.

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TL:DR

Can you shorten?

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2 stories within the same universe, both dealing with Equestrian history.

1st story: Building Equestria - Story of Celestia and Luna uniting the various tribes of Equestria for them to be the sole rulers. Many of the common folk believe them to be rightful rulers cause their victory over Discord and the fact that they're alicorns. Most of the story revolves around them slowly uniting Equestria against ponies like Princess Platinum's heirs and such. Luna forms the Lunar Guard which does work behind the shadows. A cult worships black magic and has NMM's 'birth' as a prophecy, more of a secondary plotline. Luna eventually loses most of her guards to Sombra; Celestia who has done the more official work gets most of the praise. Story ends with the scene from the show with minorly altered speech.

2nd story: Not a true sequel. Dream Guard is formed after Luna's banishment. Story takes place about 250 years after formation/Luna's banishment. Dream Guard is mostly seen as a joke. The protagonist (gender currently undecided) is a pegasus who cannot fly because they're paralyzed (wings only). However the pegasus masters lucid dreaming allowing them to fly in their dreams. That is part of the motivation to join the dream guard. They eventually get in despite being a non-unicorn. Story follows his adventures into eventual breakthrough by the dream guard into the dream plane. Eventually they contact Luna (or more accurately NMM) who proceeds to reek havoc on the minds of ponies via their dreams. They eventually win against her, seal the dream plane and forbid the practice of such magic. Celestia thanks them for their efforts and disbands the dream guard.

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Very interesting. I'm a really bad writer but i could promote your ideas.

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You're free to do what you wish with these ideas, be it writing or promoting. If I could turnout these stories and do them justice I would, but I've got plenty of other ideas and am not confident enough in my writing to tackle multiple stories at one time.

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I feel the same way. I'l promote them when I get the chance don't worry.