The King of Fighters '99 for the PlayStation does a decent job of reproducing just about every aspect of SNK's original game. The PlayStation version is clearly based on the original home cartridge version of The King of Fighters '99, as it features the exact same play modes - team play, single play, single all, and practice - and no others, though it does have a few superficial bonus options like a voice-sample "gallery," a concept art gallery, and a character color edit mode. The PlayStation version is also missing a few frames of animation here and there, and some of the voice samples sound muffled - but it's otherwise a decent, no-frills port. Unfortunately, it's a port of a game that was rather disappointing to begin with, especially if you've played the previous game in the series, The King of Fighters '98.
The King of Fighters '99 on the PlayStation looks about as good as it did on the NeoGeo. The PlayStation version features all of the original game's background stages and all of the characters; many of them suffer from minor animation cuts, and though a certain few, like the cuts on Terry Bogard's crouching light kick and Ryo Sakazaki's standing strong kick, are especially obvious, none of the animation cuts have any serious effect on the way the game plays. The PlayStation version doesn't have any new characters or backgrounds, but it does faithfully reproduce The King of Fighters '99's stages. Unfortunately, most of the original game's stages weren't terribly interesting to begin with; for instance, the "open sewer filled with brown water" stage is about as unappealing and unexciting on the PlayStation as it was on the NeoGeo.
The King of Fighters '99 on the PlayStation features all of the original game's voice samples and sound effects. Unfortunately, many of the game's voice samples sound distorted and scratchy, and when a character is subjected to a rapid attack, he or she will utter repeated, chopped-up samples instead of letting loose a single cry of pain, as in the original NeoGeo version. Regardless, the game's muffled voice samples contrast oddly with the game's clear-sounding music - which is nothing less than the full arranged soundtrack of the original game. Unfortunately, many of the actual tracks are among the most boring and forgettable ever to appear in this series. They consist mostly of half-hearted techno music, except for Terry Bogard's jazzy but entirely too laid-back theme, which is, as in the original NeoGeo version, lifted directly from the Fatal Fury: Wild Ambition soundtrack.
Despite its graphics and sound issues, the PlayStation version does a good job of reproducing the gameplay of the original version. SNK's original The King of Fighters '99 was itself a solid fighting game that borrowed much from its predecessor but was a disappointment when compared with it. The King of Fighters '98 featured two very different modes of play, and it let you choose four different character colors and four different win poses. The King of Fighters '99 only features one play mode (that most closely resembles the advanced mode from '98), and it only lets you choose two colors and three win poses per character. In addition, The King of Fighters '98 featured 38 playable characters, plus 13 alternate versions of existing characters, for a total of 51 choices, so you were bound to find at least a few characters you'd want to play. In contrast, The King of Fighters '99 features 33 playable characters, but three of these are variations of Kyo, and one is the game's boss character and official fashion disaster, Krizalid. Krizalid happens to be one of the worst boss characters ever to appear in a fighting game; he's stiffly animated, freakishly ugly, and absurdly overpowered. All these drawbacks grant him the most dreaded ability a fighting game boss character can possess - the power to completely drain all the fun out of the game the moment you face him.
To be fair, The King of Fighters '99 features five all-new characters (K', Maxima, Whip, Bao, and Jhun Hoon) in addition to Krizalid, and though some, like the insanely complex Jhun, are interesting, they don't have the same impact that more established characters - like the USA Sports Heroes and New Face Team - had. And though The King of Fighters '99's core gameplay is extremely similar to The King of Fighters '98's excellent game engine, many of the characters that did make the jump from '98 to '99 seem stripped down. Some characters simply "forgot" certain special attacks, while others were changed drastically and, in some cases, lost many of the interesting strategies and depth they once had. SNK presumably made these changes to balance gameplay between one-on-one fighting and the use of strikers, which are extra characters that can be summoned to leap onscreen, perform a single attack, and then leave.
The striker system was clearly derived from the tag system found in Capcom's Marvel fighting games, and though strikers can be used to set up a few interesting combination attacks for a certain few characters (and occasionally as a last-resort defense), they really don't add much to the game. And, despite the fact that The King of Fighters '99 for the PlayStation doesn't feature any hidden striker characters, the game has fairly substantial load times between fights with different characters, as you might expect. However, if you play the game in single-play or single-all mode, you'll be able to play a set number of rounds against the same opponent with no load time whatsoever between the rounds.
The King of Fighters '99 for the PlayStation is a fairly good port in and of itself, especially considering the limitations of the aging PlayStation hardware. It features all of the background stages of the original game, as well as the full arranged soundtrack. Unfortunately, the game's voice samples are distorted and the animations are short a few frames. Otherwise, it's a decent port - but it's a decent port of an inherently disappointing game.