The objective of the game is defined by the game mode in use.
In capture the flag maps, the objective for both teams is to obtain a briefcase of intelligence from the enemy team's base and return it to their own base while preventing the opposing team from doing the same.
Control point modes are more varied in their objectives, but share the common aim of capturing a particular point on the map. In some levels, the objective for both teams is to secure all the points on the map. On other levels (attack/defend), one team already holds all the points and must defend them from the other for a set amount of time. A more complex variation (territorial control), introduced with the map "Hydro", is based on territory: each team must capture the other team's single active control point to secure that section of the map. Once all sections have been captured by one team, they are then able to attack the other team's base directly. In an update on August 13, 2009, Valve included a fourth control point variation: King of the Hill. In this mode, both RED and BLU have to capture the center point and defend it for a set amount of time before the opposing team does. When a team gains control of the point, their timer starts to count down. If the other team captures the point, the former team's count down is stopped, and the latter team's starts.
In payload maps, one team has to work to escort a rail cart carrying a bomb along a track through a series of checkpoints, eventually detonating the bomb in the other team's base. The other team has to defend their positions and prevent the cart from reaching the end within a set amount of time. In the payload race variation, both RED and BLU attempt to escort a payload along symmetric (either parallel or opposing) tracks. The payload mode was introduced in April 2008 with the map "Gold Rush"; payload race was released in May 2009 with the map "Pipeline".
Arena is a team deathmatch mode. Arena maps focus on smaller environments and no respawning after the death of a player's character. A team wins in arena by eliminating all of the other side's members in the arena or capturing the map's central control point. Arena was introduced in the August 2008 update.