This a special story challenge I would like to present to anypony that's interested, if you wish to try it out please PM me! Here it goes:

Title: War of the Races.
Main characters: Princess Twilight Sparkle, Spike, The main Six.
Genre: Alternate Universe, Dark, Adventure.
Canonical Placement: After Equestria Girls.

Premise: While studying the Mirror Portal, Twilightattempt's to cast a spell to help her see into other worlds through the mirror, however the portal reacts negatively to her magic and ends up warping her and Spike into an alternate dimension...

When the two awaken, they find themselves in a world where the "Fire of Friendship." never shined, and the three Pony Races are at war with one another, each race having built their own kingdoms in place of the other worlds major location:

Pegasopolis:
Ruler: Princess Cadence (She is not an alicorn in this reality)
Founded by Commander Hurricane. It replaces Cloudsdale in this reality, shaped more like a kingdom. While consists almost entirely of clouds, it is built to withstand even the strongest hurricanes. This Kingdom sits close to the peak of a mountain plateau where the "Wonderbolt Academy" was. However in this reality it is a prison for non-pegasus ponies.

Unicornia:
Ruler: Prince Blueblood
Founded by Princess Platinum.This Kingdom replaces Canterlot in this reality, however instead of on the mountainside, it rests at the base on the opposite side, facing away from Ponyville.The gates of Canterlot castle separate the more "high-class" ponies from the "commoners". It's also has a special cave leading to abandoned mines that lead to the Diamond Dogs mines (who let them pass in exchange for crystals), allowing them to launch sneak attacks on their enemy's.

Ponyville:
Ruler: ???
Founded by Chancellor Puddinghead. While in the same place as the original Ponyville, it separated from the outside world by a massive wall. Despite not having magic, they hold several means of combating the other races, such as magic inhibitor collars for Unicorns, and specialized nets for holding Pegasus'.

Twilight's Princesshood is put to the test when the three tribes starts targeting her in hopes of capturing her and using her as means of winning the war! Now she must find a way to unite the three tribes and get back to her own world! But why has the war gone on for so long? Is their hatred really that thick, or is someone else pulling the strings...?

2940039
There's actually a fic that's tackling something very similar to this already called "A World Apart."

Maybe ponyville would be lead by Applejack? Or Diamond Tiara's dad.

Or a really aggressive warrior-like Big Mac.

2942721
2942759
So are you too done badmouthing a movie that has little to nothing to do with this story idea?!

3034884
Then kindly take your annoying banter somewhere else!

2940039

I'm actually doing something similar to this, except it's vice versa. A unicorn soldier from an alternate dimension goes to the canon world. Where he must learn the magic of friendship.

3190081

Interesting, did you ever think about merging the two ideas?

3190198
Yeah, you're idea would be good for a sequel. Thing is, Blueblood from the alternate world is the unicorn's comrade and he is the opposite of high class. Plus, the locations of the three territories are different to your version.

3190226
Hmmm...maybe we could discuss this further via PM?