Survival (Fallout 4)

Survival mode is the most difficult gameplay mode in Fallout 4. It differs significantly from the other gameplay modes. The mode was added to the game for all platforms on March 29, 2016. It replaced the existing Survival difficulty, which was renamed to Very Hard.

Survival mode
Survival mode can be accessed in the options menu. Unlike Hardcore mode used in Fallout: New Vegas, Survival mode can be set before gameplay. This mode also cannot be toggled freely. Once Survival mode is activated, turning it off will permanently disable it from being reactivated for that save file.

List of features
Features in this mode are as follows:
 * Sleeping in any bed for one hour is the only way to save the game, as all other methods of saving are disabled.
 * The exit save can only be loaded once when restarting the game. The save is automatically inaccessible once loaded.
 * Fast travel is disabled.
 * Teleporting in and out of the Institute works much more differently: the player can teleport into the Institute anywhere, and the player can teleport out of the Institute only to the C.I.T. ruins.
 * The Sole Survivor takes and deals increased damage.
 * Enemies now yield twice as much experience.
 * Most threats are not visible on the compass.
 * Locations of interest are harder to detect.
 * A new perk, Adrenaline, is automatically given to the Sole Survivor. It gives the Sole Survivor damage bonuses provided he or she does not sleep.
 * The Sole Survivor must stay hydrated, eat periodically, and have a regular sleep cycle in order to survive.
 * While the Sole Survivor is hungry, all foods lose their healing properties and do not regain them until enough is consumed to make the survivor "well-fed." The amount of food that must be eaten to do this is relative to its quality (or price), i.e, a ribeye steak removes hunger better than a grilled radroach.
 * Fatigue damage reduces Action points (AP).
 * Sleeping in a bed for less than 7 hours does not heal Hit Points (HP).
 * Illness and antibiotics are introduced.
 * The healing rates of RadAway, stimpaks and other healing items are significantly reduced.
 * Using RadAway and chems can negatively affect the immune system.
 * Limbs no longer heal after combat and must be restored with a stimpak, by sleeping in a bed until the Sole Survivor is well rested, or by visiting a doctor.
 * Rank 3 of Adamantium Skeleton lifts this effect, as it makes the Sole Survivor's limbs unable to be crippled.
 * Ammunition has weight and total carry weight is significantly reduced for both the Sole Survivor and their companions.
 * Downed companions will not get back up if downed in combat until healed. If left unattended, they will return to their most recent settlement to recover.
 * 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.
 * Locations take 35 in-game days for non-cleared locations and 80 in-game days for cleared locations to repopulate enemies and loot.
 * Stronger enemies now spawn with regularity, making the Commonwealth a very dangerous place until very high levels.
 * Use of console commands is disabled.
 * Workshop capacity is reduced, and it may affect the availability of production items.

Gameplay differences


Wellness
There are five stages in each category of wellness that span in-game hours. It does not seem 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.

Thirst
''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.''


 * It is possible to drink directly from manual water pumps, water fountains and open water sources such as puddles and rivers. Drinking from irradiated sources has the possibility of giving the drinker illness(es).
 * The Sole Survivor can fill empty glass containers with dirty or purified water. Dirty water is obtained from sources such as rivers, puddles or ponds. Purified water is obtained from water pumps and water fountains. The affected glass containers are: beer bottles, empty milk bottles, Gwinnett ale bottles, Gwinnett lager bottles, liquor bottles, Nuka-Cola bottles and vodka bottles.

Hunger
''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.''


 * Bonuses granted by food are only given if eaten while not currently being hungry, as stated on the game's loading screen. However, eating something that grants a bonus (e.g. the +1 Agility of deathclaw steak) while hungry will remove the bonus if it is already active. For example, eating a deathclaw steak while not hungry to gain the bonus, then become Peckish, then eating a second deathclaw steak to become well-fed will negate the +1 Agility bonus and would require eating a third deathclaw steak to regain it.
 * Certain foods, such as soups and certain crops, satisfy both hunger and thirst.
 * Issue #9 of the Wasteland Survival Guide doubles the meat dropped by most animals in the Commonwealth. This can significantly impact the amount of available food, so getting it early on in Sunshine Tidings co-op can be beneficial.

Sleep
''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.''


 * Sleeping at least one hour on any bed, mattress or sleeping bag will save the game, and remove any Fatigue the player has developed.
 * The Sole Survivor cannot sleep more than 3 hours in a sleeping bag and more than 5 hours on a mattress. To sleep for longer amounts of time, it is required to use a real bed.
 * Sleeping seven hours in a full bed ensures being well rested and minimizes risk of illness. For a quick save at a key location, sleep for at least 3 hours. Being only asleep for one hour in any bed, even at a workshop settlement, will still grant a high risk for illness, in particular parasites. Lethargy, insomnia, and weakness are also common with not sleeping well.

Illnesses

 * There is a high probability for contracting parasites during melee attacks on infected animals, in particular radroaches and mongrels.
 * All illnesses can be cured by a doctor using the 15 cap "Cure Me" option in their dialogue. This is preferable over spending the caps on antibiotic supplies. It is therefore also recommended to have at least a level 1 clinic at the main settlement to use upon return.

Bugs

 * Starting in Survival mode and later changing the game mode will not change the water production from Water Purifiers.
 * When first joining the Railroad after completing Tradecraft, the message "You can now fast travel to and from Railroad HQ" still appears, despite the fact that fast travel is disabled in Survival mode.