Knockout Kings 2003 introduces a brand new style of gameplay: Slugfest! For the first time in the history of the franchise, gamers will be able to take on opponents in tournaments with in-game milestones, earned rewards and more! Gamers will experience arcade style boxing with an over-the-top attitude. On screen cues will spur fighters on as they earn progressive damage levels for user selectable special punches, which can be unleashed on your opponent at any time. New levels of strategy are introduced, as each fighter positions himself to take advantage of these new fight options. Players can take on the Artificial Intelligence in a traditional boxing match, or slip on the gloves in Slugfest for 8 consecutive opponents with no recovery time between matches.
The game features the sport's most coveted legends and current champions, including boxers exclusive to Knockout Kings 2003 like Muhammad Ali, Joe Frazier, Sugar Ray Leonard, Lennox Lewis and Oscar De La Hoya. Felix "Tito" Trinidad, Zab Judah, Floyd Mayweather Jr. and Fernando Vargas also are featured with a myriad of fictional boxers, each with his own unique persona, attributes, strengths and weaknesses. In total, more than 40 licensed and non-licensed boxers are available to choose from or players can create their own.
The Career Mode allows the user to build a boxer from scratch with the create-a-player feature. After creating a boxer by selecting skin color, facial hair, trunks, and more, gamers develop and manage their boxer's career by building up attributes with points earned in the ring as you work your way up in rank. The multi-player tournament mode allows gamers to go head-to-head with up to 8 players vying for the championship belt.
Exciting commentary and analysis from Larry Michael and Max Kellerman keep the gamer informed on what is happening in the ring. Referees in the game include Mills Lane and Richard Steele, keeping things fair by calling out low blows and backhands that can lose a fighter points from the judges' card. Jimmy Lennon Jr. makes ring announcements, just like fight night.