Abstract
Problem: What did each SPECIAL attribute actually do under the hood in the original Fallout? Online wikis are incomplete or incorrect.
Approach: Tim Cain shares a detailed breakdown from his own post-ship notes, covering every systemic (code-level) effect of each attribute — excluding perk prerequisites, scripted checks, and dialogue gates.
Findings: Strength, Perception, Endurance, and Agility are mechanically dense stats with wide-reaching effects. Intelligence controls skill point growth and reading speed. Charisma is notably thin — only affecting speech, barter, NPC reactions, and companion limits. Luck has surprising depth, influencing criticals, gambling, special encounters, and even eye-shot blindness resistance.
Key insight: Agility was the most powerful stat due to action points and armor class alone, while Charisma was a justified dump stat — something Cain says he would redesign today.
Source
Context
Tim Cain explains that roughly a year prior, he detailed Luck's mechanics in a Reddit comment and realized he still had a document he wrote around Fallout's ship date listing exactly what every attribute did. He went looking for the original handwritten notes (with drawings) but believes a box was lost during a COVID-era pod move where hired movers may have accidentally left it with a junk pile. The digital copies survive, but the physical originals — including notes from the cancelled "Rags to Riches" project — are gone.
He also shows an original Fallout t-shirt that still says "GURPS" on it, never worn, found during the search.
Strength
- Improves base skill in Unarmed and Melee
- Increases hit points, melee damage, and carry weight (derived stats, automatic)
- Being below a weapon's minimum Strength reduces hit chance by a penalty per point below the threshold
- Increases the range of thrown weapons (grenades, throwing knives, etc.) — this is additive with the Heave Ho perk, so combining both lets you throw very far
Perception
- Improves base skill in First Aid, Doctor, Lockpick, and Traps
- Increases sequence in combat (higher Perception = earlier turn in turn-based order)
- Increases the no-penalty radius for ranged and thrown weapon distance — normally, the farther a target is, the lower your to-hit chance; high Perception pushes out the point at which the distance penalty begins, making far-away shots less penalized
Endurance
- Improves base skill in Outdoorsman
- Increases hit points and heal rate (more HP and faster healing)
- Increases base radiation resistance and poison resistance (additive with armor and consumables)
- Reduces the chance of advancing to the next radiation sickness level — radiation in Fallout worked by periodically checking if you should move up one sickness tier; high Endurance slowed this progression (never to zero, but noticeably)
- Reduces critical hit effects on the player: chance of knockout from critical headshots, chance of crippling from arm/leg shots, and chance of knockdown/knockout from groin shots are all reduced by Endurance
Charisma
- Improves base skill in Speech and Barter
- Improves NPC base reaction to you (adjusted further by actions and reputation)
- Limits the number of companions you can have simultaneously
That's it. Cain acknowledges this is why players use it as a dump stat, and says he would change this if remaking Fallout today.
Intelligence
- Improves base skill in First Aid, Doctor, Science, Repair, and Outdoorsman
- Increases skill points per level — this compounds massively, making low-Intelligence characters painful to build since you already start with five skills below normal
- Modifies conversation options (some require high Intelligence; low Intelligence gives "dumb" dialogue)
- Controls how long it takes to read a book — higher Intelligence means faster reading time (the fade-out/fade-in sequence where time passes is shorter). Cain notes he doesn't know if anyone ever noticed or cared about this
Agility
- Improves base skill in Small Guns, Big Guns, Energy Weapons, Unarmed, Melee, Throwing, Sneak, Lockpick, Steal, and Traps — a very long list
- Increases action points per combat round
- Increases armor class
Cain calls Agility "the stat" — on paper it looks like it only does a few things, but action points alone make it arguably the most powerful attribute in the game.
Luck
Luck has surprising mechanical depth:
- Base attribute for the Gambling skill
- Increases the chance of a critical success on any skill roll, both in and out of combat (pickpocketing, lockpicking, first aid, etc.)
- In combat: increases chance of critical hit on any attack, and decreases chance of critical failure
- Breaks sequence ties — if two combatants have the same sequence number (from Perception), the one with higher Luck goes first
- Increases the chance that a ranged attack using the Sniper perk becomes a critical hit (additive with the perk — Luck does nothing for this without the perk)
- On the world map: adds to the chance of special random encounters, with minimum Luck thresholds for certain encounters — this is why some players never found the flying saucer or the Nuka-Cola truck (Luck 1 locks you out of several special encounters)
- Reduces the chance of being blinded by an eye shot — high-Luck characters almost never get blinded
Notable Bug
Fallout shipped with a bug: you could get critical successes and failures on skill rolls, but not on attribute checks. This meant things like the chess game against ZAX (the supercomputer in the Glow), which checked against a skill for critical success, could literally never trigger a critical. Cain isn't sure if this was ever patched by Interplay, but hopes modders fixed it — he notes it would have been trivial to fix.