There are some detailes shared by Bethesda about Fallout 4 Survival Mode which you can read below:
- Strategy: Intensify decisions involving when to get into combat versus when to avoid it, and also make you think more about what gear to take into combat. Then back up those decisions with faster, more brutal fights.
- Exploration: Slow down the pace of the game and encourage players to explore the nooks and crannies of the world.
- Resource Management: Balance out items in the world that may be too easy to acquire or horde, giving players more to consider when planning their current loadout.
- Role Playing: Increase the realism of the world and the issues one might face there.
These 4 goals are the main pillars of Fallout 4 Survival Mode and Bethesda took some actions to achieve them. You can read the changes that has been made below:
- Saving with Sleep: The only way to save your game is to find a bed and sleep at least 1 hour. The main reason behind this move is of course make you more considerable about your actions and give you a hard time. All quicksave and almost all aoutosave options are disabled
- No More Fast Travel: Move,move, move Soldier! Yep, the only way to go wherever you want is to walk. There is no fast travel option in Survival Mode. All are diasabled because that way you have to wander around and explore the Wasteland.
- Increased Lethality: Yes, now you will have to deal more damage. Increased Lethality and Saving with Sleep combination is deadly. What can you do? It is Survival Mode. Your enemies are now more powerful.
This has an even bigger effect on melee players, who will now need to use their block/parry to keep themselves from taking damage during fights.
- Facing the Unknown: You will no longer see the threats on the compass. Surprise! Along with that, the distance at which locations of interest will appear has been significantly shortened. You will have no idea what is going to hit you.
- Adrenaline: Adrenaline is a new perk comes along with Survival Mode.
Every five kills increases your Adrenaline rank, adding 5% bonus damage for up to an extra 50% damage at the max rank of 10.
- Wellness – Exhaustion, Hunger, Thirst: If you are suffering from one of these for a long time, your health will be effected. Your S.P.E.C.I.A.L stats will be hurt, your immunity will get lower and you may be deal with physical damage. Now you are a princess.
- Fatigue: Fatigue works like Radiation but affects your Action Points. Fatigue mostly comes from being tired, but both hunger and thirst also affect it.
After reading this, I feel so vulnerable. I can never be safe in Wasteland! Not anymore! But wait, there is more. There are some adjustments to items and conditions.
- Bed Types: Real beds (rare) offer the highest bonuses for sleeping. This means you will recover more while sleeping in a real bed. And this means, you will start to spend caps for beds.
- Illness & Antibiotics: First of all, Stimpaks are no longer fix everything! There are several illnesses you can be effected. Antibiotics can be crafted, bought or found. Also, a doctor can heal you.
- Immunodeficiency: Items that cleanse your body of Rads come with the cost of making you tired and temporarily damaging your immunity, leaving you more vulnerable to Illness than usual.
- Slower Healing: What detailed information do you need about this?!
- Crippled Limbs: Crippled limbs will not heal after the combats. They can only be healed by Stimpank of sleeping.
- Carry Weight: Stimpaks and ammo now have weight and your total carry weight has been reduced.
- Painful Encumbrance: If you are carrying too much weight, you will finally get crippled. THIS.
- Companion Costs: Carry weight for companions has been decreased and they will no longer automatically get back up if downed during combat. Guess what? They will return home.
- Enemy and Loot Repopulation: Locations you've cleared will now repopulate with new enemies and loot at a significantly slower rate.
You can visit here and get more detailed information about Fallout 4 Survival Mode Beta.