Nier Reincarnation[a] was a 2021 role-playing video game developed by Applibot and published by Square Enix for Android and iOS devices.

Set in a realm called the Cage, the game followed the story arcs of multiple characters, each exploring their troubled pasts while manipulated by a greater outside threat.

Journalists gave mixed reviews praising the writing, art design and music, while frequently criticizing the gacha system.

[3] The player, controlling different characters in each arc, navigated different areas of the Cage in the company of ghost-like companions, entering statues called Scarecrows and reliving memories which play out as storybook-like narratives.

The goal was to collect coins and items that grant buffs within a time limit, while avoiding obstacles and enemies which decrease the player's score.

Both are transported to the Cage from their world and guided by two new ghost-like beings dubbed "Mama" and "Papa", Yuzuki and Hina respectively restore the broken moon and sun.

Escaping with the Mama's help, the Cage is revealed to be the Lunar Server, created to preserve human history.

On Earth, Pod 006 et al. discover multiple large towers, similar in design to the Cage itself, called the Birdhouse.

She used the Red Girl's power to construct towers resembling the aliens' homeworld, which had a similar transformative effect on the Cage.

Wanting to destroy the memory of humanity, and seeing it as bringing nothing but suffering, She sent viruses into the Cage, which take the form of the little black birds.

Lastly, She sent the data constructs Papa and Dark Mama to manipulate Hina and Yuzuki, respectively, into opening a gateway for Her to access the Lunar Server from Earth, which is represented in the Cage as the Sun and the Moon eclipsing.

[19] In contrast to the other Nier titles, the writing was handled a team of other writers, with Yoko's role being to take their ideas and create a coherent plot out of them.

[14] The narrative structure was built around short stories to alleviate Yoko's frustration at needing to extend his earlier mobile game SINoALICE beyond its planned finale due to its popularity.

[16] The second arc was written by Yuki Wada based on a draft by Yoko,[12][23] and during its early stages, the two leads' middle school days were going to be shown.

[21] An important element of Reincarnation's development was preserving the established art style and atmosphere of previous Nier titles.

While the main game used 3D graphics, the Weapon Stories used a side-scrolling style with recitation-based narration based on kamishibai (紙芝居).

The leads were designed to contrast each other, using the series' recurring black and white color scheme with gold accents to unify them.

[27] The gameplay was designed to resemble a mode in Nier: Automata where players could equip chips which automatically performed some actions.

[21] Speaking about the gacha incorporation, Yoko stated that he understood the need for inclusion despite neither understanding the business end or partaking in those designs, but kept up active communication with the staff so he could create the game he wanted within those constraints.

Character animations for the Cage sections, which were intended to be realistic, were hand-animated to ensure as little clipping or awkward movement as possible.

[29] A core part of the game design was enabling rapid transitions between different locations and into or out of battle, with the team using middleware tools to speed up processing and UI display.

[32] Due to being created for a mobile game, the music was made less dramatic than earlier home console entries, with a minimalist ambient style compared by Okabe to "diving into a spiritual world".

[23] Yoko requested a broader musical style for the second arc's score, with the instrumentation becoming less ambient and the battle theme incorporating electronica.

[35] The game's UI was designed around that translation from the start, with a challenge being fitting English versions of the dialogue into the text boxes.

[42] Matsukawa stated the international version would be essentially identical to the Japanese release, with balance adjustments to the gacha system.

[24] A novelization of the first story arc co-written by Yoko and Jun Eishima, NieR Reincarnation: The Girl and the Monster, was published by Square Enix on March 31, 2022.

[7] Jason Guisao of Game Informer, while noting the use of complex terminology, praised the narrative's overarching theme of grief and atonement.

[61] Kazuma Hashimoto of Siliconera, while mixed on the game's other elements, was pulled in by the story and characters, similarly praising its theme of loss.

[7] Guisao lauded the art direction and character design,[6] Hashimoto described the game as "beautiful" visually despite some unclear UI elements.

[7] Walton noted the gacha system's generosity compared to other mobile titles, and said he enjoyed the combat despite a lack of innovative elements.