Everyone familiar with the Fallout franchise has been confronted with the SPECIAL stats and in all games it has considerable influence on your character. If Fallout Shelter is your first Fallout game, the name SPECIAL is actually combination of the first letters of all stats a character in Fallout can have: Strength, Perception, Endurance, Charisma, Intelligence, Agility and Luck. First, I would like to explain what each stat does in this particular Fallout game and then on which stats you should focus in my opinion!
Strength is a stat that improves the damage dealt by your dweller, so high strength can useful for the defending of your vault, as well as exploring the wasteland. Some wasteland events also require strength like breaking open lockers and boxes. Dwellers with high strength will also perform better in your Power Generator and Nuclear Generator.
Perception raises the hit chance in combat and helps you find locations in the wasteland. It also seems to help you pick locks and safes. Dwellers with high perception are best for the Water Treatment and Water Purification rooms.
Endurance makes sure your dwellers can take a hit. It increases the amount of health points, radiation- and damage resistance. Later on in the game Endurance will also benefit your Nuka-Cola production in the Nuka-Cola Bottler.
Smooth talking (or better Charisma) will make sure less time is needed for baby making, although this process is quite quick with low charisma anyway. Charisma is also used for some wasteland events and it will speed up the recruiting of new dwellers in the Radio room.
High Intelligence will speed up the production in the Medbay and the Science lab. In this case especially the Medbay production is nice because that means you regenerate stim packs faster so you can equip them to your wasteland explorers.
Agility is used for improved speed in the Diner and Garden. It’s also used in the wasteland to run from an unbeatable opponent and of course, the agility events.
The level of luck increases the amount and chance on caps when finishing production. It also increases the chance on successfully rushing a production room.
Which SPECIAL stats are most important?
I’ll start off with the short answer which is: Endurance (1) and Luck (2) are the two most important stats. Both of these stats come on top because of the benefit they have the ability to improve your weapon and outfit drops/finds in the wasteland.
First of all, Endurance will lengthen your stay in the wasteland because it will increase your health and radiation resistance. And thus it will increase your chance in loot. Secondly, Luck simply increases your chance of a drop event. It also increases the chance of the drop being Rare or Legendary.
When both Endurance and Luck are maxed out, Luck takes over first place and it will be better to have a surplus of Luck instead of Endurance.
The following stats are in order of importance: Strength, Perception, Agility, Intelligence and Charisma.
Good luck finding some nice loot! And you can always contact me for questions through a comment.