The King of Fighters '99: Millennium Battle, also called KOF '99, is a 1999 fighting game developed and published by SNK for the Neo Geo MVS arcade and home consoles in 1999.

The Neo Geo AES and Dreamcast versions are both included in The Kings of Fighters NESTS Hen compilation released for the PlayStation 2 in Japan alongside other ports.

Should a high score be reached, the arcade mode will offer the player an extra fight following the final boss;[3] Kyo Kusanagi or Iori Yagami.

Points won in Battle de Paradise can be transferred to The King of Fighters '99: Evolution to speed up the leveling process for the Extra Strikers.

K' is introduced as the game's new protagonist with his partner, Maxima, who joins forces with Kyo's former teammates Benimaru Nikaido and Shingo Yabuki to form the new Hero Team.

The new Female Fighters Teams is composed of Art of Fighting guests King and Kasumi Todoh, Fatal Fury characters Blue Mary and Li Xiangfei with the latter making her debut in the KOF franchise.

The story of the new protagonist K' in The King of Fighters '99 set to be the beginning, Kono already planned the narrative to be further explored in at least two installment and exceed the fans' expectations.

[13] The designs in general were retouched to give a cooler emphasis, most notably in K' as his sophisticated style is meant to breath new life into the series.

[15] As the game was developed at the same time as SNK's Garou: Mark of the Wolves, the protagonist's designer was fearing he was too similar to Rock Howard which made him nervous.

[16] There were also similarities with Cool from the fighting game The Fallen Angels as its designers moved to SNK to work in The King of Fighters '99.

Kyo and Iori were originally designed by Shinichi Morioka who had left Steel Hearts after The Fallen Angels and upon returning to SNK for The King of Fighters '99, he also created K' and Maxima.

[18] Kyo and Iori were supposed to disappear due to business reasons or the requests of enthusiastic fans, but in the end they have continued to appear ever since.

The same issue would happen in the third story arc, where Kyo and Iori are major characters opposing The King of Fighters 2003 lead Ash Crimson but more due to narrative intended reasons rather than fan demand.

[19] Kyo was redesigned for this game for the first time in the entire series replacing his school uniform with more casual clothing that were well received by the staff and fans.

This idea was abandoned, but they later created a tribute to it in The King of Fighters 2000 by introducing Rocky, a character from Robo Army, as a Striker for Maxima.

[25] In writing the characters, Akihiko Ureshino sees the leads K' and Maxima as accidental allies due to their need to defeat NESTS being a coincidence.

[33] The Neo Geo AES version was added via emulation to the Wii Virtual Console in Japan on 18 December 2012 in North America on 16 May 2013 and in the PAL region on 4 July 2013.

[38] The Neo Geo and Dreamcast versions are included in the compilation The Kings of Fighters NESTS Hen released for the PlayStation 2 in Japan.

[46] In GameSpot's article "The History of SNK", KOF '99: Evolution was described as one of the best fighting games on the Dreamcast with Garou: Mark of the Wolves.

[57] RPGFan listed as one of the best games of 1999, comparable to Capcom's Street Fighter III thanks to the focus of new combo possiblities and regared Kyo Kusanagi's design was one of the best works by SNK.

[55] IGN's Anthony Chau commented that although "people are probably tired of 2D fighting games, saying that they all play the same", he found KOF '99: Evolution to be very distinct.

[48][55] A GamePro writer felt that the Neo Geo's quality was not handled well by the PlayStation, resulting in issues with the graphics and long loading times.

[48] HardcoreGaming noted that while the Dreamcast port of the game was superior based on its graphics and loading times, the PlayStation version was still worth playing.

[12] Uvejuegos stated that while the game did not have a major update of its characters, except Kyo Kusanagi's redesign, it still managed to maintain its quality due to its fighting system.

[2] Gaming Age felt the graphic update was more noticeable than the Uvejuegos did but was critical of Krizalid as a result of how difficult he is to beat when compared to the famous previous Rugal Bernstein and Orochi.

[49] Greg Orlando reviewed the Dreamcast version of the game for Next Generation, rating it two stars out of five, and stated that "This King of Fighters should consider abdicating the throne.

"[51] The emulated Nintendo Switch version has garnered a similar response, with reviewers finding it modern and praising its gameplay.

[54] In retrospect, 1UP.com said that while players were bothered by Kyo and Iori's exclusion from teams, and by the Striker system, K's inclusion was one of SNK's best decisions due to his fighting style.