I'm going to make an update to this post with more ideas in a few hours, and I'm posting the first part to this new thread.
wall of text incoming:
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PART I: BACKSTORY
After Skyrim's plot, [censored] hit the fan all over Tamriel. In order to keep things neutral, the Dragonborn and all the Dragons simply fade away shortly after Alduin and Miraak are killed. However, the Dark Brotherhood still kills the Emperor, and the Civil War is 'resolved' by Tullius and Ulfric both killing each other at the same time, with all possible battles happening.
This means that Skyrim and the Nords become very, very unpopular with the rest of the world, leading to further fighting there, and the formation of a serious power vacuum in Cyrodiil. This leads to the military and political strength of the Empire weakening drastically, and while much of the Legion is dead or still fighting in Skyrim, the Aldmeri Dominion simply sail on up the Niben River and sack the Imperial City with little resistance. The White-Gold Tower is demolished, and with a Second White-Gold Concordat, the Empire is officially ended, and Cyrodiil is made Dominion territory. The Imperials are forced out of their own homes, rounded up into the ruins of the Ayleids to be kept as slaves or simply killed.
The Dominion, aided by the An-Xileel of Black Marsh, begin an invasion into Morrowind, greedy for more land and the purging of another 'impure race' from Tamriel. Cornered on all sides, Dark Elf civilization is overrun and extinguished after a long and violent war. In the year 4e239, the Second Great War ends at Red Mountain, where the final resistance of the Dunmer is thwarted by the Dominion, and the people of Morrowind are reduced to slaves for the High Elves and Argonians.
Skyrim was mostly spared in this Second Great War, but are forced to fight off attacks from within by the Falmer, who rise out of the ground and raid the holds, killing thousands before they were driven back. This, luckily, made the prospect of fighting a war with both the feral elves and the battle-tested Nords very unpleasant for the Dominion, who simply withdrew from Skyrim altogether.
Attempts to conquer High Rock and Hammerfell failed miserably, as the Redguards have a secret up their sleeves: sword-singing. Though poorly-documented, it was the Redguard's trump card in the First Great War, and what spared them from the Second One. This was thanks to the actions of one Stargel Hazdad, a priest turned solider who managed not only to find the lost hall where the art of sword-singing was taught in Hammerfell, but also managed to find a way to teach it to his men and master it himself.
His actions in both reviving the ancient art of his people, then using it to save them from invasion made him a national hero thought to be the coming of the HoonDing, especially among the tribal nomads and war-ravaged communities of the south. The royal houses and Crown/Forebear factions saw it as a threat of enormous magnitude to their power, and quickly found ways to appease Stargel and his Ansei warriors.
However, power and fame corrupt, and he began using the sword-singer army he created to enforce a strict code of law based on ancient Yokuda's system, backed by a single punishment for all crimes - swift death by decapitation. Under this law, only those who were sword-singers could own a weapon, and homosixuality, worship of non-Redguard gods, and being an outlander are all considered crimes. Though Hammerfell's old rulers, the Crowns and Forebears, are still very powerful, they fear the Ansei and allow them to act with impunity. To make matters worse, Stargel found a way to master the technique of Pankratosword. After demonstrating this technique by entirely destroying the island of Stirk with it in the year 4e212, agreements of peace were quickly forged between Hammerfell and the Dominion, with the city of Rihad given to the Thalmor as a bargaining chip.
After the Second Great War, the political climate began to settle down, and the Dominion went to work rebuilding on its new land and making it more suitable for the Altmer people. Slavery is widespread across the Dominion and in Black Marsh. In the wake of the great violence, military fascism has taken grip over much of Tamriel, excepting High Rock, Skyrim and Hammerfell, who managed to preserve their culture to some extent despite the many decades of war.
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PART II: CHARACTER CREATION
To recap, [censored] has hit the fan since your adventures in Skyrim, and Tamriel is now a much different place. It's been 50 years. A Second Great War happened, and resulted in the destruction of the Empire, the genocide and enslavement of the Imperials and Dark Elves, and the rise of sharia law in Hammerfell.
The year is 4e254, on the 25th day of Sun's Height.
Things are looking bad, especially for the new character you, the player, get to control. Why, you ask? Because he or she just got a disturbing letter. Your estranged twin brother has been killed in Sentinel, and the last letter he wrote has been delivered to you by his killer, one Stargel Hazdad. His last wish to you is to take his ashes and spread them to the sea outside Wayrest, the city in which you both lived. Imprisoned by revenge and the honor of family, your character takes the next boat to Sentinel, knowing not what awaits them.
The character creation process begins with the whole race/face/name thing before you step off the boat and onto the docks of Sentinel. From there, the game prompts you to open the various menus to get a feel for them, by which you, the player, learns about the letter that prompted your adventure in the first place. This begins the main quest, and lets you open the journal and save the game. This quest is very simple: inquire about your brother's death and find a way to obtain his ashes. Asking around Sentinel's bazaar quickly leads you to the tavern written in the letter, and you find the mosque where your brother died is on the far side of town.
As it turns out, the man who killed your brother was expecting you to come back for his ashes, and placed members of his order both in the tavern and outside the mosque, tasked to kill you on sight. Regardless of which place you visit first (or at all), the first set of these thugs will always try to kill you with sword-singing, and killing them will entice a strange Dunmer woman to speak to you. As it turns out, she knew your brother well, maybe even better than you did. He was not a business man/mer/cat/lizard at all, but a high-ranking member of the Blades, spymaster of Storm Talon Temple in High Rock. The Blades, she tells you, quickly reverted to espionage and private investigation soon after the Dragons left and the Second Great War began, and spread out to their old bases in High Rock and Hammerfell, with a new goal not to hunt dragons, but to revive the Empire and return peace to the world.
His 'business trip' to Sentinel was in truth a visit to Wind-Scour Temple to meet with its spymaster to discuss a disturbing report he had received, which he believed was of great importance. She knows this because she came to Sentinel with him, and in a moment of hesitation allowed him to be killed. For obvious reasons, he never was able to deliver this information, and your new friend wants you to take the letter you have to the hidden temple of the Blades. Not wanting to draw any more attention, she hands you a cryptic map, makes herself invisible, and leaves the city.
Going into the mosque reveals that the man who killed your brother also killed everyone else inside, and not a trace of your brother's corpse is anywhere. Your brother's killer did, however, leave you another letter, in which he tells you that your brother's body was thrown into the sea, and that his head will look wonderful on his wall in the Hall of the Virtues of War. He will eagerly sell it to you, should you live long enough to meet him in person, but the price is a duel to the death. What started as a grim mission to take your murdered twin home is now a quest for vengeance, wrapped in the intrigue of a brave new world, in which you will find power beyond your wildest imagination.
This finishes character creation, and you are now free to do as you please in the desert land of Hammerfell.
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Hammerfell is a cool setting too, and a warm desert with an African/Middle Eastern theme would be a cool contrast to cold and European themed Skyrim.