Fallout: New Vegas Karma

Karma is the reflection of all good and evil choices you make during the game and how they are perceived by the inhabitants of the wasteland.

Karma levels
You begin the game with a value of zero, which increases or decreases based on the players actions. There are 5 levels of karma:

Overviews
Karma doesn't have as much of effect on gameplay as in Fallout, Fallout 2 and Fallout 3, since reputation has a more important place.

However, it does still exist and if someone catches you performing an action that causes negative Karma against their faction you will often lose reputation with that faction; for example, stealing something from The Silver Rush where a Van Graff can see you. They may also become openly hostile despite your reputation with them not being lowered enough for you to be considered hated where they will attack you.

Karma's basic mechanics work similarly to the way they do in Fallout 3 (a 2001 point linear scale with -1000 being the most evil and +1000 the most good). Unlike reputation, where one can only gain fame or gain infamy, karma can be gained and lost.

Karma also no longer determines which companions you can recruit. However, when opening a conversation with Cass after she has joined you and when you have substantially negative karma (-100) she will complain about your behavior. You will get a second warning when your karma is even lower (-150). After that, she won't complain anymore, as long as the player stays neutral. When you continue on your path to "the dark side" and talk to her again while having evil karma (-250) she will leave for good. Note that Cass does not actually grant the player any grace period to improve their karma, so a player who doesn't know better can alienate her in the space of minutes by making three attempts in a row to converse with her. Even though she will agree to accompany an evil character, the first attempt to talk with her (which you will need to do in order to tell her to travel with you) will result in her telling the player that they "can be a real asshole sometimes" and the first of three strikes will be used up on the spot.

The values for karma gain may be bugged; currently killing Very Evil NPCs (such as Vulpes Inculta) gives only 2 karma, yet killing some Fiends and Feral Ghouls grants 100 karma.

Some ending narration in the game's epilogue will also depend upon the player's karma. (See Fallout: New Vegas endings for details.)

Karma titles
Your karma status is defined by a "karma title", depending of your karma points and on your level. Though each of the add-ons raise the level cap by five, titles do not change past level 30.

To increase karma to Good or Very Good

 * Go inside Vault 3 and kill some Fiends or go inside the NCR Correctional Facility and kill some Powder Gangers.
 * Give Med-X to Boxcars, the injured Powder Ganger, inside Nipton general store. Note, you can only do this once.

Maintain Neutral karma

 * Kill Fiends or Powder Gangers if your karma is too low.
 * Steal items if your karma is too high.

To decrease karma to Evil or Very Evil

 * Steal items. (This can subtract Karma as many times as the player wishes by stealing from an owned container, replacing the item, exiting, and stealing it again.)
 * Go on a killing spree in a faction.
 * Access an owned computer terminal (which can subtract Karma as many times as the player wishes).