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 medical brace or a doctor's bag, or visit a medic. In addition, recruited companions can die permanently, whereas they are only rendered unconscious in normal mode.

The Hardcore mode can be toggled on and off at any time through the options menu.

For playing the whole game from start to finish in Hardcore mode, you get the Hardcore achievement/trophy.