Officially, the 2004 version of King of Fighters does not exist, a beautiful team of programmers (Dragon, a Korean dev team) began in the idea of ​​not breaking the annual rythm of annual release of the serie. KOF 2004 (of its true name Kof Special Edition 2004) is a very advanced KOF 2002 hack.
We can say it, for an "amateur" version (go, we will be nice we will say semi-pro), this 2004 edition remains of a very good level. But you will have a hard time playing it or finding the MVS cartridge of this hack because it remains rare. But if you ever cross it in a smoky room, stop, play a game and tell yourself that it has not been done by pros. In my eyes, it forces respect.