Capture the Flag (or CTF) is a gamemode in the Team Fortress series. Unlike CTF mode in other games, the flag will return to the base after 60 seconds have passed.
Most CTF maps are composed of two identical bases. In each base is a room that contains the flag (flag room) and about two or so respawn points. One respawn point is near the front of the base, while the second one is closer to the flag room. Each respawn room contains about three or so Backpacks that will refill a person's health, Armor and Ammo to its max. Some maps also contain Backpacks outside of spawn rooms. These backpacks contain less items than one found at a respawn room, and occasionally can be picked up by both teams.
Each base also contains a Capture Point. This is where a flag must be taken to in order to score points. In most maps, the Capture Point is not where the flag is, which can be confusing for those new to a map. However, later maps, such as the ones in TF2, simplify things by putting the Capture Point where the flag is.
The area that divides the two bases is called the Yard. The yard is usually flown past via jumping techniques such as Concjumping. It also usually has an alternate route to the enemy base, such as a water access. However, if a flag has been taken and is dropped outside, there is usually a fierce battle between attackers and defenders. The Yard also has many spots for Snipers, so attackers must be careful when exiting their base if the enemy team has a few Snipers.
The key to winning CTF is to have strong defense and offense. If your offense is weak, then your team will be unable to gain many points. If your defense is weak, your team will be steamrolled by the enemy's offense. In general, fast classes are attackers, while slow classes are defenders. The Soldier is the exception, as he can function well as a defender and attacker, though he is slightly better as a defender.
When playing offense, make it your priority to get to the flag as quick as possible. Do not fight anyone unless you have to. If enemy defense contains too many powerful classes, then you should enlist a Demoman, Heavy or Soldier to help either distract enemies or clear out the way. Most flag capturers are Scouts
Powerful but slow classes, such as the Soldier and Heavy, should be used for defense. They should be placed at chokepoints, such as a tight corridor that leads to the flag. Tight corridors make it hard for fast classes to move around and the smallness of the area makes most defender's weapons very deadly.
Engineers are vital for keeping a good offense. Their Sentry Guns can quickly kill fast classes, such as the Scout and Medic. As with the other classes, Sentry Guns should be placed at chokepoint to maximize their effectiveness.
Demomen can be very useful if used right. The Pipebomb Launcher can be used to cover a flag as the last line of defense. About 3-4 Pipebombs can take out a Scout and/or Medic.
Some CTF variants exist. Here are a few:
In Shutdown-style maps, there is a barrier (often laser) that protects the flag. In order to get to the flag, a switch somewhere in the map must be touched. When it is hit, the barrier will be down for 30–60 seconds, depending on the map. During this time, the attackers must make a strong push to the flag in order to get to the flag within the time limit. A common strategy is to have one person run in and grab the flag, then toss the flag away from the barrier is reactivated.
Rock-style CTF maps play somewhat differently than the average CTF map. Instead of a flag, the attackers must grab a key in the enemy's base and take it to a point in the enemy's base. Once the point is reached, there will be a very small countdown before instant-kill nerve gas will be released in both bases. During the countdown, a few Biosuits are available to be picked up. However, there is a very small amount of time before the gas is released are there are not enough Biosuits for an entire team. Once the gas is released, the key will be reset.
In Reverse CTF, a team must take their flag to a capture point in the enemy's base. Otherwise, it is the same as regular CTF.