Niflheim

The Empire of Niflheim is a nation in the world of Eos in Final Fantasy XV. It has achieved world domination bar the Kingdom of Lucis that has defended itself with the Crystal's power. Tenebrae has limited autonomy from Niflheim due to the Oracle Lady Lunafreya Nox Fleuret, who has the power to commune with the gods. Niflheim is technologically adept and advanced than most nations of the world due to their knowledge on magitek, and automobiles originate from Niflheim, although the cars made in Lucis appear more advanced.

Story
In the aftermath of the Great War of Old some two thousand years ago, Niflheim was one of four countries created from the ashes of Solheim. Solheim was a civilization that dominated Eos and was overthrown by the Astral god of fire, Ifrit. He had broken rank from the other Astrals and turned on mankind.

Aspiring to recreate the domination of the ancient civilization of Solheim, the Aldercapt family initiated its policy of expansion, declared themselves as emperors of Niflheim, and begin declaring war on neighboring countries to annex them.

In the year M.E. 359, Niflheim conquered the land of Tenebrae, except the Fenestala Manor, home to the Oracle lineage of House Fleuret.

By the year M.E. 725, the entire world, bar the continent and country of Lucis, is under imperial rule, although Accordo is allowed relative autonomy. Emperor Iedolas Aldercapt has begun the mass production of magitek soldiers for the forthcoming all-out war with Lucis, whose crown city is protected by a magic barrier upheld by the king. Emperor Iedolas was, for a long time, a benevolent ruler and loved by the masses.

In the year M.E. 756, the Emperor launches an attack on the capital of Lucis, Insomnia. The attack happens during a peace-treaty signing party which was supposed to settle the dispute and have all of the Lucian outlands annexed to the Empire in exchange for peace. The treaty-signing was a cover for the true imperial objective: the invasion of Insomnia, the theft of the Crystal and Ring of the Lucii, and the conquest of Lucis. King Regis, his son Prince Noctis and Lady Lunafreya the Oracle are all reported dead.

In truth, Luna escaped, and Noctis was not in the city when the attack took place, prompting him to seek rendezvous with Luna and start his quest to restore his kingdom and save the Crystal. Niflheim begins constructing military bases to Lucian territory and raids the town of Lestallum while looking for the exiled prince. Niflheim attacks the astral god Titan in Cauthess, but Prince Noctis forges a covenant with the deity, and begins demolishing the newly-constructed bases with his friends.

Aranea Highwind is a mercenary who used to work as a commodore in the imperial army. When Noctis's party meets her in Tenebrae she notes that the empire "went mad" ten years ago and began the process of mixing daemons with technology. Chancellor Ardyn Izunia had introduced to Verstael how to mate daemons with human fetus material, then attached to a robotic magitek trooper frame, and encased in armor. These magitek soldiers are, with natural daemons, used indiscriminately on the battlefield.

In his death throes as the daemon Foras the Emperor laments his desire to more than just ruling Eos; by seeking to fell the astrals, the Emperor declared his hope to rule over the heavens and Eos.

The areas around Niflheim, as well as the capital city Gralea, are enshrouded in a fierce perpetual winter, and the surrounding countryside is an arctic tundra. In M.E. 745, eleven years before the events of the game, the military battled the Astral Shiva. Her frozen corpse causes a climate change in stark contrast to the original surrounding deserts and once lush forests.

Eventually the citizens of Gralea die at the hands of daemons, or are turned as daemons through the Starscourge, and Emperor Iedolas Aldercapt is turned into a demon named Foras by Chancellor Izunia. After General Glauca's defeat at the battle of Insomnia, Ravus Nox Fleuret, the former prince of Tenebrae, becomes the new high commander of the imperial army. He is tasked with felling the Leviathan, but is sentenced to the death after the sea goddess goes on a rampage around Altissia. He is later turned into a daemon. It is unknown what happened to Verstael.

Prince Noctis infiltrates Gralea during his quest to reclaim the Crystal, but finds the place devoid of humans and swarming with rogue magitek troops and daemons. He discovers the Emperor has turned into a daemon, and fells him. When he finds the Crystal in Zegnautus Keep, he is absorbed inside it for ten years, awaiting the day he would return as the True King as spoken in prophecy. After Noctis disappears the sun doesn't rise again and what is left of the empire collapses, with people migrating to Lestallum, whose power plant provides the town with light to fend of the daemons who take over the world.

Etymology
The same name origin is used for Nibelheim from the Compilation of Final Fantasy VII.

Trivia

 * An Imperial General named Safay Roth was ultimately cut during development, but a trace of him remains in the "SAF" lettering on Niflheim's landing crafts. Proceeding this, Ardyn's position was added as villain.