Hardcore Mode

 is an optional gameplay mode in Fallout: New Vegas which introduces new, challenging aspects of survival into the game. In this mode, stimpaks heal over time, RadAway removes radiation over time, ammunition has weight, and the Courier must stay hydrated, eat periodically, and have a regular sleep cycle. Food only staves off hunger and heals you over time. To restore critically damaged limbs, you must use a doctor's bag, hydra, or visit a doctor. Sleeping in unowned beds does not fully heal your character. In addition, recruited companions can die permanently, whereas they are only rendered unconscious in casual mode.

The Hardcore mode can be toggled off at any time through the options menu. Once turned off, it can be turned back on, although keep in mind that the player will be unable to receive the corresponding achievement (mentioned below). It is initially available after the character creation screen just before you leave on your journey.

For playing the main quest line from start to finish in Hardcore mode, you get the Hardcore achievement / trophy.

Bugs

 * The cause is still unknown, but sometimes one or more of the Hardcore needs (such as H20, FOD, SLP) will disappear, and will not even indicate a 0 integer. But you can fix it by going into the options then turning hardcore off/on again and that will reset all of your needs to 0. But this seems to be a redundant problem once it happens the first time, and starts upon loading a save. A way to fix it is to make a backup save, and delete the old file.