This arcade fighting game by SNK was called KOF '99 "Evolution" when ported to the Dreamcast (see entry 1284), and I guess the "Evolution" was the unlockable "Extra" strikers in the DC version, because they're absent from the PS1 port. Regular strikers--and I assume all the other gameplay innovations of '99--are still here.
Load times are much better in this than in SNK's early PS1 KOF ports, but while the gameplay initially seems quite brisk, it can really bog down depending on what's going on in a fight. Yuck. Also, in team mode, your teammates aren't shown in the background watching you fight, which sounds like a small detail, but it WAS a staple for most of the series, and it's kind of a bummer not to see them.
There is a "single all" quasi-survival mode here. The real cool extra mode is the art gallery, though, which has a large section of unused KOF art, including alternate designs for some of the new characters (a *lot* for would-be new poster boy K'...looks like they had a tough time settling on what he was going to be), alternate costume designs for new and old characters, and even designs for possible new characters who never made it past the "gleam in the eye" stage. If you like this gallery, check out the PS1 port of KOF '98 (see entry 143), which has a similarly cool one.
Not really so fun to play with the slowdown in this version, though.
Oh yeah, there's also a Color Edit mode here. Heck, the Dreamcast version didn't have any such thing, so if you're a sprite coloring wizard, this would be your version to get...eh except probably for some later PS2 port or something.
This version doesn't have the white screen strobe effect that other versions--the one in NESTS Compilation on PS2, for instance--have when a match ends with a striker or special move; the PS1 version just goes to a white background that then fades away or whatnot, no strobing involved. I stopped playing the NESTS version because that strobe was bothering me; but I can play this version! : )