The King of Fighters '99
The game contains unused music that was likely meant for the standard and MVS title screen sequence.
The original Kyo was redesigned for the game, but some designers wanted his iconic school uniform. When they were nearing the end of their production schedule, staff members were indecisive upon which uniform the Kyo clone should wear (KOF '94 or KOF '95). When the project head said to just make two clones instead, the game’s staff objected due to time constraints. In response, the project head then drew designs for Kyo-1 and Kyo-2 on the spot to resolve the issue.
Kyo and Iori were originally not planned to be in the game so that the story could focus on the newer characters. However, it was ultimately concluded that the characters were popular enough that they couldn’t just leave them in limbo, so they got a reprieve as well as a redesign.
K′ and Maxima are directly inspired by Cool and Harry Ness from the unfinished arcade game, The Fallen Angels. The designer for the Fallen Angel characters, Shin'ichi Morioka, migrated to SNK shortly after the game's failed release and used elements of Cool and Harry Ness to design the KOF duo.