Includes a mode where additional level of simulation, limitations, etc. are added. Often also making things matter that didn't before and making earlier somewhat trivially removed ailments harder to get rid of.
Alternate name: Ironman mode
The first video game about Hardcore mode was released on September 1994.
* Permanent death
* Injuries or even plain damage can only be healed at a doctor and possibly not even that well there
* Addiction can't be cured instantly
* Hunger & thirst is added
* Fast travel is disabled or limited
* Things that normally are weightless now actually have it (e.g. ammunition).
* Experience is limited or benefits of levelling are reduced.
* Character level is capped (lower)
* Usable items are more scarce
If only one or very few things are changed (unless it's a significant one, like permadeath) then it might not be worth tagging the game with this.