Final Fantasy XI R, formerly known as Final Fantasy XI mobile or Final Fantasy XI Reboot, was a planned mobile remake of the 2002 Playstation 2 title Final Fantasy XI. The mobile game was announced in March 2015 as a part of the Vana'diel Project.
The game was being developed by Korean company Nexon and was originally slated for a 2016 release in Japan and Korea; though as time went on the game received little to no public development updates until reports in late 2020 claimed its cancellation, which was officially confirmed early 2021.
On March 19, 2015, Square Enix announced a full fledged Final Fantasy XI experience on a native mobile app as part of the Vana'diel Project, which included Rhapsodies of Vana'diel, intended to be the last major revision to the game, and Final Fantasy Grandmasters, another mobile game. The project was to be led by Nexon, a Korean mobile game developer, and touted touch-based interface and upgrades to systems such as Parties and Skillchains. The project was to release sometime in 2016.
On April 27, 2016, Nexon unveiled the first screenshots of the mobile game, titled Final Fantasy XI Reboot, at the Nexon Developer Conference, featuring what appeared to be a redesigned Windurst and Sarutabaruta. It was revealed that the game would run on Unreal Engine 4.
Although little official news were released for the game since NDC 2016, Nexon continued to actively hire for roles relating to the development of the game through their careers portal.
In May 2018, Nexon continued to list the game, now under the simple title Final Fantasy XI mobile, in its financial reports, claiming the game was still under development. During 2018, development of the game moved to an internal studio at Nexon, named Nexon One Studio, with the game's direction drastically changing to a trading card RPG focus under director Sim Gi Hoon, with internal estimates pegging the game for a 2019 release. 
A letter to Nexon's shareholders released on 25 March 2019 briefly mentioned the game as still being under development, stating that the company's partnership with Square Enix has been difficult but fruitful. During this period, the game appeared in Nexon's company roadmap under the new title Final Fantasy XI R.
In early 2020, the developers of Final Fantasy XI were asked about the title but were unable to comment on it. In mid-2020, screenshots from in-development versions of the game came to light from the portfolio of a development member but were quickly taken down by Nexon.
In December 2020, Korean financial news network MTN announced in an exclusive report that the project had been cancelled, with staff previously working on the game being reassigned to other Nexon projects. The report claimed developmental difficulties and drastic internal directional shake-ups paired with communication issues with Square Enix that were exacerbated with the advent of the COVID-19 pandemic. Square Enix refused to comment on the state of the project.
On 9 February 2021, Nexon had their investor presentation for Q4 2020, where for the first time since its inclusion in 2018 the project was absent from their pipeline. When asked by teleconference about the project's status, Nexon president and CEO, Owen Mahoney, acknowledged its cancellation, and claimed that both Nexon and Square Enix agreed to relocate staff formerly working on the project to other works, citing the game as having not reached the level fans expected of a game in the Final Fantasy series.
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- 22 March 2021. ネクソン、『ファイナルファンタジー XI R』開発プロジェクト中止 クリエイティビティの観点から期待水準に達していない. GameBiz.jp. Archived from the original on 23 March 2021.