Source: © YouTube: "NieR Re[in]carnation （ニーアリィンカーネーション）: Promotion Movie【クローズドβテスト開催決定】"

A closer look at NieR Re[in]carnation, a new smartphone game by creator Yoko Taro

NieR Re[in]carnation (henceforth referred to as "Rein") is a new installment in the overall Yokoverse, or timeline that spans multiple video games and other media created by Yoko Taro. We don't need to get into those details in this article, but if anyone is curious about specifics, you can find an in-depth view of the timeline here. Beware of spoilers the further down the page you go!

See also: Be sure to check out the additional articles I've written about Yoko Taro and his works here.

What We Currently Know About the Game

To date, few details about the game have been released, but here's a quick list of what we know.

Characters

Girl in White
CV: Nagae Rika
A Sealed Mind, Dreams of Another World…
When she awoke, she found herself upon the cold stone of the "Cage". Every night she sees another nightmare. A gentle and cheerful girl, what possibly could be the reason for such shackles and bandages?

Mama
CV: Hara Yumi
Thousands of Stories, Tens of Thousands of Dreams
A mysterious being named "Mama". She seems to know something about the "Cage" and provides guidance to the girl. She enjoys the scenery and poking her nose into other people's business, even overindulging in freedom.

The Black Monster
CV: Kawahara Motoyuki
Hidden Words, Lost Dreams
A mysterious being that wanders the "Cage". Although it resembles a knight in black armor, it is also not unlike a silent bug. It seems to have some purpose, but...

Here's the latest teaser trailer below, which was released on July 13!

Here are some translations for the text that is shown in the above video:

Lines Spoken by Mama:

The place where you awoke, as well as this area of sand where you find yourself now, are only part of a larger story.
It's quite a mysterious building that not much about it is known.
The atmosphere of the "Cage" has changed! Look how beautiful this place is!
The dust was so horrible back there, but the air here is absolutely delicious!
It's so bright here...! But, we've found you!

Memoryscape Sequences:

Fire rises in a town as you hear shots of gunfire.
A well-mannered boy and a silent man walking behind.
I have to find my sister!

Game Play

The game play will be a mix between traversing the "Cage" which appears to be a sort of hub world from which the player is able to access other areas. For the most part, it appears as though we have control of the Girl in White.

This may shift, however, in the "Memoryscape," a sort of separate reality that deals the memories of various characters. There is no official term for this particular in-game mechanic yet, so I'm coining this term for ease of conversation.

A well-mannered boy and a silent man trailing behind. | © YouTube: "NieR Re[in]carnation （ニーアリィンカーネーション）: Promotion Movie【クローズドβテスト開催決定】"

The Memoryscape seems to be an in-between world with a clearly different design style that somewhat reminded me of the memory sequences in Zanki Zero.

In the battle sequences, we can see several interesting things. It appears as though the party size will max at 3 characters at a time. It appears battles will be somewhat turn-based

Battles appear to be turn based, but may function more like what they've done in BladeXlord, which you can view a sample of here:

The People Behind Rein

Producer: Saito Yosuke (SQEX)
Saito has worked on previous installments in the NieR series with both NieR Gestalt & Replicant as well as NieR:Automata. He has been a true godsend when it comes to supporting Yoko Taro and his creative endeavors.
Creative Director: Yoko Taro
Yoko Taro is the creative mind behind such series as Drakengard, NieR Gestalt & Replicant, NieR:Automata, the YoRHa stage plays, and the Thou Shalt Not Die manga series (which is coming to a close next month!), among many others!
Director: Matsukawa Daichi (Applibot)
Developer: Applibot
The game will be developed by applibot, who was behind the development for another recent title that I've discussed, BladeXlord. If anyone is curious what sort of work they've done on this particular game, and how it might carry over to Rein, you can check out the little blurb that I wrote about it here.
Main Character Design: Yoshida Akihiko (CyDesignation)
Concept Art: Koda Kazuma
Music: Okabe Keiichi (MONACA)
Planning & Production: Square Enix

NieR Re[in]carnation Closed Beta Test

As mentioned in the April 30 issue of Famitsu magazine, they announced that they were planning on having a Closed Beta Test (CBT). Here are the details on that:

Applications open between Monday, July 13 12:00pm-Sunday, July 26 11:59pm
Results released between Wednesday, July 29-Wednesday 1:00pm, August 5 12:59pm
A total of 10,000 iOS and another 10,000 Android users were selected. Unfortunately, only residence in Japan were eligible to be selected for the CBT.

Although no official release date for the full game has been released yet, since the CBT will likely start sometime in August, I would assume the official release will come at least 6 months later, which will be around Q1 or Q2 of 2021.

Assorted Info

The April 30 issue of Famitsu magazine detailed a ton of information, not only on Rein, but also NieR Replicant Ver.1.22474487139... as well, which is apparently neither a remaster nor a remake but rather somewhere in between.
There will be some form of Gacha, possibly related to the characters you recruit to see their memories in the Memoryscape.
There will likely be Collaboration Gacha for characters such as Devola, Popola, and Emil from the NieR series as well as others previously unrelated to the Yokoverse.
Note: It was suggested in the Famitsu article that NieR characters may appear through this aspect of the game, but at this time, it is still purely conjecture how other non-Yoko related series may be involved.
The main character design for the Girl in White was illustrated by Yoshida Akihiko from CyDesignation, just as the main trio from NieR:Automata.
In the second half of 2018, Square Enix released a classified ad to recruit scenario writers for a new NieR related project. In the Famitsu article, Yoko Taro comments that the selected individuals, which Saito referred to as the "Yoko Team," will be working on Rein given the sheer scope of the story-related material. Hence, Rein will likely have the most text out of all the NieR games.
Yoko says there will be multiple MCs. Exactly what he means by this is currently unknown, but it may be related to the Gacha system and the Memoryscape.
Yoko: It's a mysterious game.
Unlike SINoALICE, another smartphone game by Yoko Taro that recently saw a global release earlier this month, Rein has a clear ending. I can only assume that the game will have a well-shaped beginning, middle, and eventual end, unlike many smartphone games today that seem to have no end in sight.
The gameplay will be somewhat similar to Puzzles & Dragons, where there are various stages that you have to clear in order to progress. Then again, Saito comments that it's similar, whereas Yoko disagrees.
Rein is not a PvP game, so there will be no competitive battles between players.
Rein is considered "canon" for the rest of the Yokoverse. It's not an off-shoot of anything, but is rather an authentic installment into the overall series.