Team killing

Team-killing or TKing is a term used in team-based First-person Shooters to describe players who accidentally or deliberately slay members of their own team. In the majority of case, it is a discouraged activity. Accidental TKing can happen due to inaccurate fire, bad driving, collateral damage or confusion in the heat of the moment. Deliberate TKing is usually carried out by griefers or for some concrete reward - such as to steal the player's weapon, beat them to a weapon, vehicle or objective - or else as revenge for an earlier slight. It may also be carried out for the sheer hilarity in performing a devious act, such as when one plays a prank on a friend.

Reasoning Behind Friendly Fire

Many games technically allow for friendly fire either for the sake of realism or as a method of obtaining mechanical game balance. For example, in a World War 2 simulation of an infantry battle, it would be unrealistic to throw a grenade into a mixed crowd of enemies and friendlies, expecting it to only damage enemies. In games such as Tribes 2, friendly fire may be enabled by the server administrator in order to discourage spamming of explosives.

Discouraging Intentional Friendly Fire

Most games which support friendly fire use some method to discourage intentional friendly fire, aka "team-killing". Simply, many games allow an option to disable friendly fire, preventing most TKs from being possible. However this is not always a preferred option as the reduced realism can be undesirable. Other systems involve deducting points from players for TKs or forcibly logging them off of the server.

Sample anti-TK system from Planetside:
* Damaging friendly players results in the accumulation of "Grief Points".
* Grief Points accumulate faster if many separate instances of friendly fire occur back to back -- someone who does 500 points of friendly fire damage in 1 minute suffers more than someone who does 500 points of friendly fire damage over 2 hours.
* Once grief points exceed a certain threshold, the player will no longer be able to shoot or drive lethal speeds in a vehicle.
* Grief points slowly dissipate over time.

This type of system is intended to create a chilling effect on intentional or clumsy episodes of friendly fire damage without overly punishing the occasional accident.

In addition to this system, usually, the one who is found to be intentionally killing his teammates will usually be kicked or banned from the game. This is a common practice of FPS games.

The Xbox Live player review system also allows players to negatively review and submit complaints on the grounds of disruptive game behavior. One of the most infamous team killers is TeamKiller0703. His YouTube videos have gained major popularity.