There are five default modes of combat in Unreal Tournament 2003. Additional game modes are available by downloading the Epic Bonus Pack.

Deathmatch
Players are pitted against each other in a balls-to-the-wall free-for-all. Anything goes. The one with the most kills wins.

Team Deathmatch
Join your teammates in the quest for battlefield supremacy. The team that kills the most enemy players is judged the winner.

Capture The Flag
Each level has two team flags. In order to score, one team must penetrate the opposing team's defenses, 'Capture the Flag' and return it to their home team's flag. If the flag carrier is killed, the flag drops to the ground for anyone to pick up. If your team's flag is taken, it must be returned before your team can take the opposing team's flag.

Double Domination
Each level has 2 Domination Points. In order to score, you must 'capture' each Control Point (by running over it) and keep them in your team's possession for 10 seconds. After scoring, the Control Points reset to neutral and will become available to Dominate again after another 10 seconds.

Bombing Run
Each level has one ball in the middle of the play field. The objective is to pick up the ball, deliver it to the enemy base and fire it through their goal. You must also defend your own goal to prevent the enemy from scoring. The ball is dropped when a player is killed and can then be picked up by anyone on either team.

Mutant (requires Epic Bonus Pack)
The player who makes the first frag becomes the mutant and is immediately equipped with all weapons, extra ammo, invisibility, agility and berserk. However, the mutant's health slowly decreases and can only be replenished by fragging other players. Once there is a "mutant," all other players are charged with hunting him down. Points are scored only by the mutant when they frag other players. As an optional twist, the player with the lowest score becomes the BottomFeeder -- he can frag other players who are not the mutant and receive points. As soon as his score isn't the lowest, a new player becomes the BottomFeeder.

Last Man Standing (requires Epic Bonus Pack)
This is similar to the Last Man Standing mode in the original Unreal Tournament. Players regenerate health when they frag an opponent. If a player stands in one place for too long, they will be revealed to other players as a camper and their location will appear on all opponent's displays.

Invasion (requires Epic Bonus Pack)
In this game type, players band together to defend against waves of incoming monsters -- including many of the monsters from the original Unreal. Players cannot respawn if they die during a wave, but as long as one player makes it to the end of a wave alive, everyone respawns for the next wave.