NieR Replicant

Nier is an action role-playing game in which players take on the role of a player-named protagonist; the protagonist is a middle-aged man in Nier Gestalt and a teenage boy in Nier Replicant, named by the player. The player directly controls the main character through a third-person perspective to interact with people, objects, and enemies throughout the game. The player can turn the camera around the characters, which allows for a 360° view of the surroundings. The three-dimensional world is divided into areas separated by loading screens, and the player can move freely throughout these areas by walking, running, jumping, and climbing ladders. In some rooms and buildings, the camera swings to the side, and the main character is restricted to moving as in a two-dimensional platforming environment, while during certain battles, the camera pulls up to simulate a top-down shoot 'em up or other video game genres.

While traveling the player is frequently attacked by monsters, which include shadowy figures called Shades, large animals, and robots. Defeating these enemies gives the player experience points that can increase the main character's power and money that can be used to purchase items. The player's weapons can be customized to have greater damage and abilities using materials that can be purchased, dropped from monsters, or scavenged around the world. Multiple varieties of each weapon type can be acquired.

In the mid 21st century, in the midst of a snowstorm in summer amid a ruined city, the protagonist fends off ethereal black monsters to protect a sick young girl named Yonah. The protagonist uses a magical book to fend off the creatures, but Yonah touches it and is covered in black markings, worsening her condition. The story moves to over a thousand years later, with the current feudal civilization in decline and the black creatures—dubbed Shades—becoming more hostile. The protagonist and Yonah live in a village built within post-industrial ruins, with the protagonist taking odd jobs from the village leaders, twin sisters Devola and Popola, to earn money to support the sick Yonah.

While rescuing Yonah from a temple after she wanders there looking for a rare flower, the protagonist meets the talking book Grimoire Weiss, which suggests that the two team up to use Weiss's magic and to find a cure for Yonah's disease, identified as the terminal Black Scrawl. In their search, they encounter Kainé, a hot-tempered and foul-mouthed swordswoman, and Emil, a blindfolded boy whose eyes petrify anyone they see. After journeying for a time, the protagonist's village is attacked by a giant Shade. The battle ends with Emil being forced to petrify Kainé to seal the shade, and Yonah being kidnapped by a master Shade dubbed the Shadowlord.

The concept that would become Nier was first proposed following the release of Drakengard 2 and the reveal of seventh-generation consoles. The original concept was for a third entry in the Drakengard series. As the project evolved, the original ideas were reworked, and the game eventually became a spin-off from the main series. Despite this, the game's director Yoko Taro continues to think of it as the third Drakengard game.

Different reports described its planned platforms. An earlier report stated it was intended as an Xbox 360 exclusive, then expanded onto the PlayStation 3 (PS3). Yoko later stated that the PS3 version was the original one planned due to the lessening importance of the PlayStation 2, which Drakengard 2 had been made for. Including concept planning, the total development time lasted three years, with two years spent actually developing the game.

Nier Gestalt sold over 12,500 copies in Japan the week of its release, while Replicant sold over 60,000 and was the top-selling video game in Japan that week. Replicant sold over 121,000 copies in Japan by the end of May 2010 and ended the year with over 134,000 copies sold. In 2019, Yoko estimated that Nier had sold around 500,000 copies worldwide. According to Yoko, "we weren't really in the red, but it wasn't exactly a success either".

Nier received mixed reviews. Reviewers criticized the graphics, with Ryan Clements of IGN saying that "one of Nier's greatest flaws is its visuals," while GameSpot's Kevin VanOrd bemoaned the "flavorless visuals" and "lifeless environments". Dustin Quillen of 1UP.com said that the game "looks downright primitive", while Adriaan den Ouden of RPGamer, who awarded the game a higher score than most, said that "the environments are bland and poorly rendered". The music and voice acting, however, were praised; Clements said that "both are quite excellent", den Ouden called the soundtrack "absolutely fantastic", Chris Schilling of Eurogamer said that the music was full of "memorable themes", and one of the four reviewers for the Japanese Weekly Famitsu termed it "a cut above".

Nier was the last game that Cavia made; the company was absorbed into its parent company, AQ Interactive, in July 2010. Square Enix executive producer Yosuke Saito later commented that "a number of things" related to Nier were in progress and that an announcement could be due in 2011. The only announcement ended up not being for a new Nier video game, but instead for a live evening concert for Nier's music titled "Nier Night ~ Evening of Madness" which took place on October 28, 2011. In March 2011, there were plans made between Yoko and Takuya Iwasaki, one of the original producers for Drakengard, to develop a port of Nier for the PlayStation Vita at Iwasaki's company Orca.

The port would have incorporated material from both versions of the game. When Orca was chosen to help develop Dragon Quest X, the project was shelved. A number of key staff from Nier's development, including director Yoko and Okabe, would later reunite to work on a new entry (Drakengard 3) in the Drakengard series from which Nier was spun off.