Team killer

A team killer (or TKer) is a player that kills their own teammates in a multiplayer computer game. Team killers are scorned by most gamers. Since many team kills are accidental, the name team killer is usually reserved for those that repeatedly TK. Team killing usually happens in first-person shooters from friendly fire.

Why do players kill teammates? Many TKs are accidental, often committed by or against newbies. In first-person shooters, grenades are a classic source of accidental team kills. Grenades have a delay before they detonate and do splash damage, often affecting teammates that unknowingly run towards the resulting explosion. Grenades can also be thrown into areas that the player cannot see, which may contain teammates. But the most hated TKers are those that do it intentionally for the fun in causing grief to other players.

In team-based multiplayer games, administrators are usually provided the option of whether or not friendly fire should be on or off. Having friendly fire enabled makes the game more realistic and often slows the tempo forcing players to think more about what they do before they do it. Having friendly fire enabled is probably more common on private or LAN servers where it is less likely to be abused.

Many games implement punishments in order to prevent TKers from doing more damage and possibly stop them from playing the game. One of the most common punishments is to give the server administrator the ability to kick and possibly ban a player from the game server. Another is to deduct points from the TKer's score. One of the more unusual methods is "mirror damage", which inflicts all damage that the player does to a teammate back on themselves. Since most punishments are imposed for actually killing a teammate, some persistent TKers only wound teammates in order to avoid the repercussions. Often vigilante "anti-TK" players take it upon themselves to team kill the team killer, but usually end up getting penalized for TKing anyway.

Most games do not allow team killing. By default Team Fortress Classic allows teammates to do some damage to one another, but not actually kill them. Simply disallowing TKing is not always a perfect solution to the problem though. Once again in Team Fortress Classic, players can become infected (causing them to gradually lose health points until they die or are cured) and pass on that infection to teammates. Sometimes players pass the infection on to many teammates. Similarly, players might use their natural invulnerability from teammates in order to aid the opposing team. (This is more common in strategy games and computer role-playing games with player versus player combat.) Many of these issues are classified as bugs and are eventually fixed in a patch.