Survival (Fallout 4)

Survival mode is the most difficult gameplay mode in Fallout 4. It differs significantly from the other gameplay modes.

Survival mode
Survival mode can be accessed in the options menu. Unlike Hardcore modes in previous Fallout games, Survival mode can be set before gameplay. Also, this mode cannot be toggled freely. Once Survival mode is activated, turning it off will prevent you from turning it back on for that save file.

Features in this mode are as follows:
 * Manual, quicksaving and almost all autosaves are disabled. Saving must be done by sleeping.
 * The latest patch for Fallout 4 added an "exit save" feature that automatically saves a game upon quitting the game. Once the save is booted up, however, it is immediately deleted and you are forced to sleep in order to save the game again.
 * Fast travel is disabled.
 * The Sole Survivor deals, but also takes more damage.
 * Typically, threats are no longer displayed on the compass.
 * Locations of interest are harder to detect.
 * The Adrenaline perk is given.
 * Sole Survivor must stay hydrated, eat periodically, and have a regular sleep cycle.
 * Fatigue damage reduces Action points (AP).
 * Sleeping in a bed less than 7 hours does not heal Hit points (HP).
 * Illness and antibiotics are introduced.
 * The healing rate RadAway, stimpaks and other healing items is significantly reduced.
 * RadAway and chems can adversely affect the immune system.
 * Limbs no longer heal after combat and must be restored with a stimpak, sleeping in a bed until well rested, or by visiting a doctor.
 * Ammunition has weight and total carry weight is significantly reduced for both the Sole Survivor and their companions.
 * Companions will not get back up if downed in combat until healed. If left unattended, they will return home.
 * Robotic companions created in the Automatron add-on, excluding NPC robots like Ada and Jezebel, will now be destroyed if not repaired after being downed in combat.
 * Cleared locations take much longer to repopulate enemies and loot.
 * Enemies that usually spawn at higher levels will now spawn with regularity.
 * Ability to access the game console (the tilde key) and use console commands is disabled.

Gameplay differences


Wellness
There are five stages in each category of wellness that span in-game hours. It doesn't appear that the thresholds are linear. For example, it takes about 6 hours to go from well-fed to peckish to hungry, then 12 hours to go from hungry to famished. The following table shows the approximate times that it takes for a character to go from completely satisfied to the listed condition in each area. In-game time is expressed in "hours" and real-time is expressed in "minutes". These effects can be sped up when using certain items. Stimpaks and other drugs inducing dehydration, Rad-Away causing hunger, etc.

''Note: The In-game / real-time data in this table are approximations only. The time expressed is not truly accurate. This table may be incomplete''.

Bugs

 * If you start in survival mode, and later change out, your water production from purifiers will stay the same.