Developed primarily by Square Enix's exclusive CGI studio Visual Works, Kingsglaive is based on the setting and story of the video game Final Fantasy XV, which is thematically connected to the Fabula Nova Crystallis subseries.

Kingsglaive runs parallel with the events in the beginning of Final Fantasy XV, focusing on Regis Lucis Caelum CXIII, the father of main character Noctis.

The main protagonists are from the Kingsglaive, an elite combat corps who share Regis's magical powers and defend the kingdom of Lucis and its Crystal from the invading empire of Niflheim.

Faced with continued detrimental conflict, Regis accepts an armistice with Niflheim: as part of the peace treaty, his son must marry Lady Lunafreya Nox Fleuret of the imperial province of Tenebrae.

The treaty turns out to be a ruse for Niflheim to invade, and Kingsglaive soldier Nyx Ulric is caught up with Regis and Lunafreya in a battle to secure the future of Lucis.

The film's voice cast includes Gō Ayano, Shioli Kutsuna and Tsutomu Isobe in Japanese; and Aaron Paul, Lena Headey and Sean Bean in English.

Kingsglaive was made as part of a planned multimedia expansion of Final Fantasy XV to negate having to develop a series of games using the setting and characters.

Reception to the film was generally negative, with praise going to the visuals and lead actors' performances, while the story and supporting cast were widely criticized.

Twelve years later, the Kingsglaive fight to protect Lucis's borders from attacks by Niflheim's Magitek army and Daemons, unnatural monsters tamed for military use.

Regis, whose magic powers the Wall and is growing weaker due to advancing age, accepts Imperial Chancellor Ardyn Izunia's offer of peace.

Two days before the treaty is to be signed, Kingsglaive member Crowe is sent on a mission to escort Lunafreya to Altissia to meet Noctis, but is killed en route.

At a party dedicated to the signing of the treaty, attended by both Regis and Niflheim's emperor Iedolas Aldercapt, Lunafreya meets with Nyx before being secretly abducted by Glauca.

At the treaty-signing ceremony, the Niflheim delegation springs a surprise attack and kills the ruling council, while their army enters by destroying the Wall with help from the rebels, who are subsequently massacred.

He is confronted by the spirits of the past kings of Lucis; initially rejected due to being not of their bloodline, his resolve and the threat to the Crystal persuade them to allow his use of their power at the cost of his life.

With the Ring's borrowed power he engages Glauca in a titanic battle throughout Insomnia, animating the city's statues of past rulers, known as the "Old Wall", to combat Niflheim's Daemons.

[35] Nozue later commented that another aspect of Kingsglaive was to bolster sales of the game's platforms prior to release, with a film offering a greater means of reaching potential buyers.

[36] The story of Kingsglaive was based around a portion of the original opening of Final Fantasy XV, which would have shown the invasion of Insomnia by Niflheim's army.

[41] According to Nozue, another key element during the early segment of the film was displaying how the world's society sees Regis's responsibilities, along with the emotions involved in such a role.

[46] Nyx was an original character created for the film with no connection to the events of the game, intended to act as a medium for the wider audience Kingsglaive was aimed at.

[40] As with other Japanese CGI films aiming for a realistic tone, the team relied on photogrammetry and an extensive 3D scanning process combined with motion capture.

[8][23][25] Most of the film's individual props such as the car, Nyx's daggers, the Niflheim mechs and the Ring of the Lucii were created and rendered before main production had begun.

As Nozue wanted to use the experience and technology of Visual Works to create Kingsglaive, they decided to bring in experienced and dedicated outside help to handle V-Ray.

This resulted in the cooperation with Digic Pictures, which included former staff from Square Enix's North American branch and were highly skilled in the creation of high-quality cutscenes.

Due to the themes and events of Kingsglaive, Graham needed his music to reflect the weight, contradictions, and shifting "light and dark" perspectives of the characters and locations.

[71] Meghan Sullivan, writing for IGN, gave the film a score of 6/10, calling it "gorgeous", and praised the character design despite some issues with realistic facial expressions, and found the story was bogged down by the political elements when the action side and the plot focusing on the Kingsglaive worked.

In contrast, she called the voicework "solid", saying that the leads brought their characters to life and prevented the script from sounding too ridiculous while the supporting cast was weaker overall.

[72] Andrew Barker for Variety frequently questioned whether Kingsglaive could count as a film, as he often felt like he was watching a recorded gameplay video, praising the visuals while generally faulting the plot as rushed and too full of throwaway characters.

His criticism was leveled at its poor portrayal of the female characters, a narrative he found confusing, and the large focus on setting up the events of Final Fantasy XV.

[77] In contrast to the majority of reviewers, Anthony John Agnello of GamesRadar gave the film five out of five stars, calling it "an expert blend of world building, humanity, and the magical strangeness of Final Fantasy" and praising it for balancing its scene setting for Final Fantasy XV with creating a relatable experience, in addition to lauding its visuals and relatable characters.

[78] GameSpot's Alexa Ray Corriea was also fairly positive: while she noted that it was not a coherent film on its own, she felt that it was a first step by Square Enix to regain fan trust after earlier missteps.