While there are a few similarities between the two games, Foes of Ali was developed by a different team, Gray Matter, and as such, is not regarded as a precursor.

In Knockout Kings, the boxer sprites, although distinctive, are not facially representative of their real-life counterparts.

However, 2 aspects that Knockout Kings has which the sequels lack is that the referee does a mandatory eight-count when a fighter is knocked down whereas in the sequels the referee stops the count immediately after a fighter gets up from a knockdown, and, in Career Mode, the result of a fight is afterwards seen on the screen as front-page newspaper headlines.

The Knockout Kings game series gives users a chance to compete against numerous real fighters, such as Muhammad Ali, Eric Esch, Marvin Hagler, Sugar Ray Leonard, Oscar De La Hoya, Larry Holmes, Jake LaMotta, Roberto Durán, Alexis Argüello, and Ray Mancini.

Fake amateur boxing legends, such as Daryl ‘Hotcakes’ McGee, The Great Smokey Maggard, Boto Bondingo, and Flute Top Terry, could also be unlocked by gaining certain achievements.

In Knockout Kings 2000 for the PS, the boxer sprites are for the first time facially representative of their real-life counterparts.

Injury to the face of boxers can also be recognized, as well as his mouth-piece flying out if he is hit by a hard punch.

Knockout Kings 2002 changes many concepts of its predecessors, e.g. users have to progress through a number of bouts in order to unlock new fighters.