CYOA-based (Maybe just a setting?)

Unicorn (5/5) - Blank Vellum
Companion (Pegasus) - Feather Duster (10/15)
Utility Magic (5/20) & Vision-range teleport (5/25)
Light Magic (5/30), Fire Magic (5/35), & Earth Magic (5/40) ('Learned' from Twilight before entering Everfree)
Civilization (5/45)
Community [Talent/Cutie Mark] - Tattered scroll (Ancient History) (5/50)

Planet is now divided between five powers after an event several thousand years ago (technology has stagnated in that time span):
  Cadance (The Sensual Empress)
  Celestia (The Unconquered Sun)
  Luna (The Living Dream)
  Twilight (The Hoarder of Knowledge)
  Discord (The God of Madness)
North is Cadance. East is Celestia. West is Luna. South is Twilight. Center is the now-massive Everfree Forest and Discord.

Each get their power from their domains:
  Cadance: Love and Lust (Becomes more attractive)
  Celestia: Worship (Becomes more regal)
  Luna: When she sleeps, feeds on dreams (Stored in gems?) collected from sleeping ponies/griffins/etc during the night  (nocturnal) (Appearance changes [varies depending on the kind the majority of dreams she fed off of])
  Twilight: Knowledge (Becomes more draconic in appearance due to her hoarding of knowledge [due to the loss of books, ponies not sharing knowledge after the split, and her not wanting the knowledge to be lost] and connection to Spike [while dragons have long lifespans, they're not immortal: Spike has been dead for several centuries, while Twilight sleeps next to his preserved corpse in her 'study,' which is the size of a small town])
  Discord: Chaos (Becomes eldritch/immaterial/just WRONG in appearance)

North: Paradise of lust and debauchery in the empire itself; the land outside is still a frozen, desolate wasteland in order to make the empire more enticing
East: Militaristic, worships Celestia as God-Queen
West: Lawless, kill or be killed
South: Nobody knows. All that go there never return. (Twilight rips the minds from anything that enters her province, takes the knowledge, and fills their heads with the knowledge she's collected in order to make 'friends' and leaves them babbling incoherently)
Center: Malforms living things into grotesque, violent caricatures of what they once were. They used to attack all provinces, but no longer attack the South (Maybe never attacked South?).
Border Communities: Usually have well-defined, yet rather lenient laws. Value Harmony over what's valued on either side of borders. Have more in common with pre-split Equestria than current areas.



Companion
 •Feather Duster
  ~Cutie Mark is a wing above a vase (Archaeology)
  ~Beige coat; short, black hair
  ~Like Vellum, born and grew up in West
  ~Unlike Vellum, is street smart.



West
 •Start off in West, rummaging through a ruined library for old books that might still be somewhat intact. However, places like the ruined library are often havens for thestrals.

 •Thestrals (Bat ponies)
  ~Gaunt, vicious night-dwellers
  ~Vampiric, but didn't used to be (Thestrals are closely connected to Luna, who, during one of the many times her form was influenced by nightmares, used magic to preserve their monstrous forms and personalities)

•Due to Luna's form (and personality) always shifting, the laws of the land are also in constant flux. Because nightmares are now so widespread, Luna's form is now almost-constantly abhorrent, which also causes an aura across the land that amplifies negative feelings.

 •Small outposts are scattered throughout West
  ~Crime is punished much like in the Old West

 •Chased out of West and into South by a gang (Savages as a name?)


South
 •Twilight
  ~Vellum takes notes while Twilight acts as living, breathing exposition
  ~Feather Duster keeps talking about how the split is antithetical to what Twilight once stood for, not letting her get a word in edgewise. "DON'T YOU THINK I KNOW THAT!?" Twilight screamed, flames licking at the back of her throat. "You want to know what happened to us!? Fine! I gave up on them! Every messenger I sent to Celestia or Luna was killed, sometimes by they themselves! I can't even contact Cadance because Discord and that damned forest of his twist my messengers beyond recognition! Do you want to know the last time ANY of them tried to contact me? It was right before... Before Spike..." The alicorn leaned against the wall before looking up with tear-filled eyes. "If they won't even try to talk to me, then why should I even try to talk to them?"

 •As they leave South and try to re-enter West, are once again accosted by gang and are, this time, forced to flee into the Everfree Forest



Center
 •Discord
  ~Losing grip on his mind, more akin to Alzheimer's than insanity (Chaos, being inherently unstable, eventually breaks down)
  ~Keeps mistaking Feather Duster for Fluttershy; is proud of how self-reliant and assertive 'Fluttershy' has become
  ~Powers have grown at a far slower rate than the Alicorns' due to Harmony (While the split signifies a breakdown of Harmony, the fact that the areas have had roughly-defined borders for over a thousand years is a kind of order, lessening the spread of Chaos)

 •Envoy (of Discord)
  ~Has mouths for eyes, still has regular vision
  ~All three mouths argue with each other constantly, except when relaying what Discord has said. Then, they speak as one.
  ~Other than mouths, looks like a normal pegasus.

 •Flora and Fauna:
  ~Ferns with fronds that look like ridged bones (like picture on phone)
  ~Ambulatory, herbivorous plants
  ~Trees with thick trunks and leaf-heavy branches; none of which provide shade
  ~Chimeras, but made up of random animals (e.g. short otter legs, stout bear torso, fish head and tail)
  ~Timberwolves made of stone
  ~Innocuous-looking animals that cause vivid hallucinations when touched (Bird that lands on Feather Duster; not played for humor, is terrifying for her)
  ~



North
 •Has an ever-present aura that lowers inhibitions (maybe from Crystal Heart?); Main characters have to stave off its influence.
  ~Feather Duster falls to temptation for a short while, tries to seduce a barely-lucid Vellum. A tentative smack from Vellum knocks her out of it, at which point she flat-out punches him, busting his lip.

 •Cadance
  ~Focuses mainly on Feather when they enter her throne room
  ~Freaks when Vellum says "Sunshine, sunshine, ladybugs awake..." Hugs both with wings, starts crying
  ~Still loves Twilight as a little sister; still loves the late 'Shiny'
  ~"After Shiny passed, I could never lay with another stallion," the alicorn said, almost whispering, as she rubbed the heart-shaped amulet around her neck.



East
 •Oracle (Title, not name) Belle
  ~Descendant of Sweetie Belle
  ~Is over a century old
  ~Eyesight was damaged by (solar flare? Eclipse?); as a result, is blind in left eye
  ~Believes that Celestia gives her divine visions; in actuality, inherited powerful scrying magic from Sweetie Belle, who had eventually become Twilight's first Royal Seer
  ~Celestia is so vain (she probably thinks this song is about her) and deluded, she believes that she IS the one giving Belle visions
  ~

 •Celestia
  ~Maybe what caused the split was that Celestia killed the other element bearers because she believed them to be corrupted by Discord (Why would she think that, though?)? Then the elements went haywire and caused Chaos to spread from the Tree of Harmony? Twilight attacks Celestia and forces her East, then retreats South? Luna, wanting to distance herself from her sister's act, goes West?
  ~Thinks that the world revolves around her
  ~Treats ponies as pawns or just so far below her that they don't even register as a blip on her radar
  ~Feather Duster to Celestia, who has been saying that the split (and her ruling) was destined to be: "Fate," the pegasus spat the word as if it were poison. "Destiny. Those are nothing but words the WEAK use to excuse their actions!" Feather Duster stomped a hoof closer to the alicorn. "The STRONG carve out the paths leading to their future, not wait around to have it just hoofed over to them! The only reason the split happened is because you were all too WEAK to even try to make a difference! And now, you all just sit in your rooms, complaining and pouting and crying about how you didn't do anything wrong! Face it, (i)Your Majesty(/i), you always have been and always will be WEAK!"