After the events of last year's tournament, Heidern is determined to investigate the NESTS cartel and put a stop to their ruthless ambitions. After his old friend Ling suggests that K' and Maxima may hold the key to locating the whereabouts of the mysterious organization, he focuses his efforts on finding them so they can be captured and interrogated. Meanwhile, NESTS sends some of their own agents to investigate this year's tournament.
Continuing from '99's Striker system, KOF 2000 expands it into the Active Striker system; instead of having to stand still to summon a Striker, 2000 lets the players to summon them under almost any situation, allowing massive combo opportunities. Each character has an alternate Striker known as "Another Striker" and a select few have a third Striker, known as a "Maniac Striker"; if they count as individual characters, this puts KOF 2000 as the installment to have the biggest roster in the entire main series, as well as having the most SNK game representation in a single fighting game (with some surprise guest appearances like Burning Fight and Quiz Daisousa-sen).
Another notable change in KOF 2000 is that, in addition to some buffs to Counter/Armor Mode, it splits up the Super Moves between the normal version and the MAX version, dropping the rule of all Super Moves having their upgraded "MAX" variation. Some Super Moves still keep both normal and MAX versions (like Iori's Ya Otome), but now each character has a Super that only works as either a normal move (costing one Power Gauge stock) or a MAX move (costing all three stocks like in '99; it would be accordingly altered in future installments to fit their system). This mechanic change was one thing that would stay in the series for a while, up until KOF XIII.
The game would eventually be ported to the Dreamcast and PlayStation 2. The former adds new stages, while the latter adds new Maniac Strikers, an alternate mode known as Party Mode, and the ability to watch the openings of past KOF titles.
- Team Hero: On the run from NESTS after the previous tournament, K' and Maxima are still looking for answers; perhaps the aid of secret agents Ramon and Vanessa will be of use to them?
- Team Benimaru: Benimaru Nikaido and Shingo Yabuki continue their search for Kyo, now joined by newcomers Lin and Seth.
- Team Fatal Fury: Terry Bogard, Andy Bogard and Joe Higashi as always, with Blue Mary replacing Mai as their fourth.
- Team Art of Fighting: Once again comprised of Ryo Sakazaki, his father Takuma and Robert Garcia; with King replacing Yuri this time around.
- Team Ikari: Leona Heidern, Ralf Jones, Clark Still and Whip officially begin their mission to bring the NESTS organisation to justice.
- Team Psycho Soldier: Same lineup as usual; Athena Asamiya, the still depowered Sie Kensou, Chin Gentsai and Bao.
- Team Women Fighters: Now consisting of regulars Mai Shiranui, Yuri Sakazaki and Kasumi Todoh, alongside newcomer Hinako Shijou, a girl who uses sumo wrestling moves.
- Team Korean Justice: Same lineup as last year, comprised of Kim Kaphwan, Chang Koehan, Choi Bounge and Jhun Hoon.
- Single Entry: Kyo Kusanagi and Iori Yagami enter solo once again.
- Bosses
- Mid-Boss: Kula Diamond, a young female agent of NESTS; genetically modified with ice powers to counter K' and his flames.
- Boss: Zero (aka Clone Zero as he's later dubbed), the sponsor and mastermind by this year's tournament plot. However, unlike Krizalid, he turns against NESTS for his own ploy for world domination.
This work shows examples of:
- Actionized Sequel: From a gameplay perspective, at least. The Active Striker system makes it much easier to chain together long combos, potentially to a point where one good hit is enough to end a round.
- Adaptation Expansion:
- The Dreamcast port adds extra stages not just from the previous KOF games, but SNK games in general. Examples include the Team Japan's stage in KOF '95, Nakoruru's stage in Samurai Shodown III, and the first stage of beat 'em up Burning Fight.
- The PlayStation 2 port adds more Maniac Strikers to some characters, like the American Sports Team and Leona/Iori in their mid-boss forms from the Orochi Saga.
- Art-Style Clash: The "retro" stages added in the Dreamcast version retain their graphics as they were, and clash with the graphical advance SNK went through in the 90s.
- Balance Buff:
- In KOF '99, your Power Gauge resets to none when your current fighter loses in previous match. In 2000, you get your stocks back again like the Advanced Mode in '98.
- The Armor Mode lasts longer than in KOF '99.
- The cooldown to recover the Power Gauge after using both Limit Break Modes became shorter than KOF '99.
- Big Bad: Zero, a traitorous NESTS agent who plans to use KOF participants' data to power the Zero Cannon. It's also revealed that he was behind Krizalid's death in the last tournament.
- Bittersweet Ending: Zero is defeated, but the Zero Cannon fires one last shot that reduces Southtown to rubble.
- The Cameo: Most of the Another Strikers and Maniac Strikers are characters from other games and SNK properties.
- Classic Cheat Code: In arcade version, Maniac Strikers are not shown by default and has to be unlocked through secret command.note
- "Freaky Friday" Flip: In Team Korea's ending, Chang and Choi end up switching bodies after taking a direct hit from the malfunctioning Zero Cannon. Rule of Funny is presumably in effect here.
- Gameplay Grading: Like '99, KOF 2000 keeps track of your performance with Battle Ability points, which determines whether and when Kula shows up as an optional boss. Unlike '99, the amount of Battle Ability points is abundant if you set the game on higher difficulty and will face Kula with little effort if you do so without continuing.
- Guest Fighter: The alternative Stirker characters (both Another and Maniac type) include the SNK characters that have not appeared in the KOF series (yet). The featured SNK games are:
- Art of Fighting: "Unknown" (Ryuhaku Todoh)
- Athena: The Goddess Athena
- Buriki One: Gai Tendo
- Burning Fight: Duke Edwards
- Fatal Fury: Duck King, Kim Dong Hwan, Kim Jae Hoon, Lilly Kane
- Fu'un Series (Savage Reign and Kizuna Encounter): King Lion, Kim Sue-Il
- The Last Blade: Kaede
- Metal Slug: Fio Germi
- Robo Army: Rocky
- Samurai Shodown: Nakoruru
- Quiz Daisousa-sen: Neo & Geo
- Miscellaneous: G-Mantle (SNK's Abandoned Mascot)
- It's a Wonderful Failure: KOF 2000 is, across all main KOF series including XV, the only installment to display unique game over quotes from your last defeated fighter, most of them lamenting their loss or declaring they're not giving up (even by Breaking the Fourth Wall and addressing the player).
- Kill and Replace: It's eventually revealed that the Ling working with Heidern is actually a clone loyal to Zero, and the original was killed by Zero.
- Kill Sat: The Zero Cannon is an orbital laser weapon powered by combat data.
- Limit Break: Armor Mode and Counter Mode return from the previous game.
- Multiple Endings: In addition to the different endings for each team, the final cutscene changes depending on whether or not the player fought Kula. If so, her handlers appear to subdue Zero, and she prepares to destroy the Zero Cannon. If the player didn't fight Kula, Heidern is seen subduing the Ling clone, preventing them from pressing a button that was presumably connected to the Zero Cannon.
- No-Holds-Barred Beatdown: One of the traits of some Strikers is that, even when the opponent went into a complete hard knowkdown state, the Strikers can forcefully stand them up and lock them into hitstun state again, opening an extra combo opportunity for the player character. The most commonly used Striker is Joe, but there are many others who can do this, like Kim Dong Hwan and Mr. Big.
- Offscreen Moment of Awesome: Kula destroying the Zero Cannon is depicted as this in other teams' endings. Averted in her ending, where it's seen in detail.
- Optional Boss: Kula Diamond is fought if the player has enough Battle Ability points before a specific point.
- Practical Taunt: Taunting with at least one bar of meter adds one stock to the Striker gauge.
- SNK Boss: Clone Zero's super meter increases incredibly fast, and his supers inflict roughly over half of your health's worth of damage, not to mention one of them being a full-screen attack. Fortunately, he's got a case of Artificial Stupidity where it's mitigated by his AI's weakness when reacting to the player, but it's still a good idea to be careful when fighting him. Still, this is by far the easiest SNK Boss in the entire series.
