Karma

What is Karma?
Karma is an estimate of the sportsmanship of the player. It serves functions revolving around how much the players are able to interact with each other, as well punishing players with poor cooperative skills.

High and Low Karma
If a player's Karma is high, it means he/she most likely stays until a game's completion, be it victory or defeat, plays as a Medic often, or plays large amounts of Nightmare Mode games.

How to Gain and Lose Karma
When a game starts, 1 karma is deducted from every player. Consider this an "Entry fee" for the match. This karma is regained upon either Victory or Defeat, but is forfeited should the player quit, or disconnect. If the player opts to random a class rather than select a specific one, they will lose 5 karma if they leave the game before death.

Losing Karma
Failing to rescue at least 20 civilians during the Civilian Escort will cause the players to lose a karma point (Admin note: Line may be outdated because I have never seen this occur in Recruit Mode and it may or may not exist in harder modes, need confirmation in harder modes before I can fully remove this line.)

Not getting to Epsilon Mining Site on time will also cause all players to lose one karma and one rating in Easy Company, all difficulties.

Killing the civilian Ramirez will cause a player to lose 1 karma, for killing an innocent civilian. However, his death rewards the player with random items, often a few stacks of Magazines.

Players will lose a large amount of karma for team killing, this includes accidental team kills such as players walking into Satchel charges or Nukes.

During the Seal the Bio-Domes section of Easy Company, all players lose 1 karma. They can gain it back by rescuing at least 20 civilians from the city.

Karmabite
If a player team kills, his victim has the option to type -Karmabite. If typed soon enough after his death, the victim can punish his killer further, reducing the killer's Experience by 100 and Karma by 25. However, if he decides the team kill was accidental or his own fault, the victim can choose not to punish further.

Gaining Karma
Dying rewards the player with 1 karma, to cover the entrance fee karma he or she lost at the start. Playing through until victory or defeat (not quitting) will grant a second karma, causing a net gain of +1.

Killing the Brain Bug Queen will award all players surviving with an additional karma, regardless of whether they helped defeat it or not. Note that the BBQ can be awakened at any time, but usually requires several players coordinating to defeat. (Not present in Easy Company Recruit Mode)

Players are awarded extra karma for playing Medic, due to their passive roles as support and healers. However, the specific criteria for this are unknown, and it is not rewarded 100% of the time.

Clearing a chapter of a campaign in Nightmare Mode grants additional karma, and winning in Nightmare rewards a large sum of karma.