Trivia
If you're wondering how to pronounce the name of KOF '99 lead character K', it's simply like this: Ki (said like key)-Dash.
In the game's Art Gallery mode, you'll see a lot of artwork for characters from previous KOF games that were set to appear in KOF '99, but never did. Among them are:
Goro Daimon (KOF '94-KOF '98), Chizuru Kagura (KOF '96-KOF '98), Athena Asamiya (in a different style than her KOF '99 style), Billy Kane (Fatal Fury-KOF '98), Ryuji Yamazaki (Real Bout FF-KOF '98), General Heidern (KOF '94-KOF '95, KOF '98), and Kyo Kusanagi (his original look from KOF '94 to KOF '98).
The only ones in this list who DID make it to KOF '99 (Athena and Kyo) have been redesigned considerably. Athena now sports shorter hair and a much nicer looking outfit, and Kyo abandoned the "school boy" look by donning a white leather jacket and jeans.