Hardcore Mode

 is an optional gameplay mode in Fallout: New Vegas that increases the challenge of 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 normal mode.

The Hardcore mode can be toggled off at any time through the options menu. Once turned off, it cannot be turned back on. It is initially available after the character creation screen just before you leave on your journey.

For playing the whole game from start to finish in Hardcore mode, you get the Hardcore achievement/trophy. With this Achievement it is possible to toggle Hardcore mode on and off at will.

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. Someone please edit this if they have more info on it. (Confirmed, PS3)