GURPS Adaptation Research: Mechanical Foundation for Salt & Steel

Document Type: Technical Research
Author: Research Specialist
Date: 2026-04-24
Status: Draft — for Architect and Lead Designer Review
Purpose: Evaluate GURPS 4th Edition as the underlying engine for Salt & Steel and propose concrete translation strategies for a real-time pirate ARPG.

GURPS Core System Deep Dive
GURPS Supplements Relevant to a Pirate ARPG
Adapting GURPS for Real-Time ARPG
What GURPS Provides That PoE Doesn't
The Salt & Steel Attribute Model
The GURPS-Inspired Skill Atlas
Combat System Translation
Probability Analysis: 3d6 vs. d20 vs. Percentile
Recommended Design Decisions

1. GURPS Core System Deep Dive

1.1 Point-Buy Character Creation

GURPS 4th Edition (Basic Set: Characters, 2004) uses a unified point-buy currency for all character aspects. A typical starting character has 100–150 points; cinematic heroes start at 200–400+. Every trait in the game has a fixed point cost, and the point total is the only gate on character power.

Point Cost Structure:

Trait Category	Cost Model	Example
Attributes	Fixed per level	ST: 10 pts/level
Secondary Stats	Fixed per level	HP: 2 pts/level
Advantages	Fixed or per-level	Combat Reflexes: 15 pts flat
Disadvantages	Negative (earn pts)	Pacifism (cannot harm innocents): -10 pts
Skills	Per-level above default	variable by difficulty
Quirks	-1 pt each, max 5	Minor personality traits

This system has profound ARPG implications: there is no class lock. A pirate can be both a swordsman and a navigator and a hedge wizard, limited only by points. Build diversity is theoretically infinite.

1.2 The Four Primary Attributes

Strength (ST) — 10 points per level (base 10)

Governs Basic Lift: ST² ÷ 5 = lbs that can be lifted overhead
Determines Thrust and Swing damage (the two base melee damage dice)
At ST 10: Thrust 1d-2, Swing 1d
At ST 15: Thrust 1d+1, Swing 2d-1
Relevant to crew intimidation, boarding actions, grappling
High ST characters are strong but costly — 10 pts/level means a ST 14 character has spent 40 points just on strength

Dexterity (DX) — 20 points per level (base 10)

Most expensive primary attribute — the "king stat" of GURPS combat
Directly feeds Basic Speed (DX + HT / 4)
Provides the default for most physical skills
A DX 14 character (+4 DX) costs 80 points — almost a full starting budget
Governs ranged accuracy, dodge potential, ship-handling finesse

Intelligence (IQ) — 20 points per level (base 10)

Most expensive cognitive attribute
Governs Will (self-control) and Perception as secondary stats by default
Provides defaults for most mental and social skills
High IQ is the gateway to effective spellcasting in standard GURPS Magic
For pirates: navigation, tactics, read maps, negotiate trade deals, curse research

Health (HT) — 10 points per level (base 10)

Governs Fatigue Points (equal to HT by default)
HT rolls used for: staying conscious when HP drops to 0 or below, resisting disease/poison, recovering from knockdown, resisting effects of extreme environment (sea cold, tropical disease)
For pirates this is the "sea legs" attribute — endurance, disease resistance, curse resistance

Why DX and IQ Cost More: Both DX and IQ each cost 20 pts/level vs. 10 for ST and HT. This reflects their broader utility — they serve as defaults for far more skills. In Salt & Steel, this cost differential must be preserved or the attribute economy collapses.

1.3 Secondary Characteristics

All secondary stats derive from primary attributes. They can be bought up or down independently at reduced cost.

Secondary Stat	Default Formula	Buy-Up Cost	Notes
Hit Points (HP)	= ST	2 pts/HP	Survivability pool
Will	= IQ	5 pts/level	Mental resistance, curse defense
Perception (Per)	= IQ	5 pts/level	Spot traps, hidden enemies, treasure
Fatigue Points (FP)	= HT	3 pts/FP	Action economy resource
Basic Speed	(DX + HT) / 4	5 pts/0.25	Initiative and dodge
Basic Move	= Basic Speed (rounded down)	5 pts/level	Hexes per turn, maps to m/s
Basic Lift	ST² ÷ 5 lb	(buy ST)	Encumbrance threshold

Encumbrance Levels (relevant for pirate loot carry):

No Load: ≤ Basic Lift
Light: ≤ 2×BL (Move -1, Dodge -1)
Medium: ≤ 3×BL (Move -2, Dodge -2)
Heavy: ≤ 6×BL (Move ×0.5, Dodge -3)
Extra Heavy: ≤ 10×BL (Move ×0.2, Dodge -4)

1.4 The 3d6 Roll-Under Mechanic

GURPS uses 3 six-sided dice summed against a target number. You succeed if your roll is at or below your skill/attribute. Margin of success (MoS) = target − roll; margin of failure (MoF) = roll − target.

Critical Success: Roll ≤ 4, or ≤ skill−10 (whichever applies first at high skill) Critical Failure: Roll ≥ 18, or ≥ skill+10 (at low skill)

The exact probability tables are analyzed in Section 8.

1.5 Skill System

GURPS has over 200 defined skills. Each skill has a difficulty rating that affects how fast it advances relative to points spent:

Difficulty	Starting Level	+1 Level Costs
Easy (E)	Attribute − 0	1 → 2 → 4 → 8 pts
Average (A)	Attribute − 1	1 → 2 → 4 → 8 pts
Hard (H)	Attribute − 2	1 → 2 → 4 → 8 pts
Very Hard (VH)	Attribute − 3	1 → 2 → 4 → 8 pts

Skill Point → Level Table (Average skill, base attribute 10):

Points Spent	Skill Level	Effective Roll Target
1	9	37.5%
2	10	50.0%
4	11	62.5%
8	12	74.1%
12	13	83.8%
16	14	90.7%
24	15	95.4%
32	16	97.7%

Skill Defaults: Skills have defined fallback levels if you have no training. Sword defaults to DX-5; Shield defaults to DX-4; Climbing defaults to DX-5. Defaults allow any character to attempt most physical tasks, just poorly.

Wildcard Skills (from GURPS Action): A single wildcard skill (e.g., "Guns!") covers an entire domain at IQ or DX without penalty. Costs 3× a Very Hard skill. These are perfect for "archetype identity" nodes on a Skill Atlas.

1.6 Advantage and Disadvantage System

Advantages are purchased with character points. They range from minor perks (1 pt) to major ability transformations (50+ pts). Disadvantages provide negative points (i.e., give you more points to spend elsewhere), limited to a maximum of −75 points in most campaigns.

Combat-Relevant Advantages (with costs):

Advantage	Cost	Effect
Combat Reflexes	15 pts	+1 active defense, +2 Fright Check, never surprised, +6 Fast-Draw
Enhanced Dodge 1–3	15 pts/level	+1 Dodge per level
Enhanced Parry 1–3	5 or 10 pts/level	+1 Parry with one or all weapons
Enhanced Block 1–3	5 pts/level	+1 Block
Weapon Master	20–45 pts	Parry at ½ skill+3; faster skill advancement with weapon type
Ambidexterity	5 pts	No off-hand penalty
Trained by a Master	30 pts	Allows use of most advanced martial arts techniques
Extra Attack 1–4	25 pts/level	One additional attack per turn
Rapid Healing	5 pts	Doubles natural healing rate
Danger Sense	15 pts	IQ roll to detect ambush; +2 to all surprise checks
Luck	15 pts	Once per hour, re-roll any roll and take best result
Extraordinary Luck	30 pts	Once per 30 minutes
Ridiculous Luck	45 pts	Once per 10 minutes
High Pain Threshold	10 pts	Ignore shock penalties from damage
Fearlessness	2 pts/level	+1 Fright Checks per level
Perfect Balance	15 pts	+4 Acrobatics/climbing, never falls from environment effects
Serendipity	15 pts/level	Once/session, improbable good thing happens
Gunslinger	25 pts	No penalty for rapid fire, no turns to aim, pistol-level accuracy at hip

Disadvantages Useful as Optional Modifiers:

Disadvantage	Value	Effect
Bad Temper	−10 pts	Self-control roll to avoid provocation
Bloodlust	−10 pts	Must try to kill incapacitated enemies
Cowardice	−10 pts	Harder Fright Checks
Cursed	−75 pts	Things go catastrophically wrong with regularity
Dependency (rum, etc.)	−varies	Penalties without regular access to substance
Greed	−15 pts	Self-control roll to resist taking treasure at all costs
One Eye	−15 pts	−1 ranged attacks, −1 all vision-based rolls
One Hand	−15 pts	Cannot use two-handed weapons; special off-hand rules
Overconfidence	−5 pts	Will roll to back down from challenges
Unluckiness	−10 pts	Once/session, GM forces worst of two rolls

1.7 Combat System

GURPS combat uses a hex-based map (1-second turns). Each combatant selects a maneuver each turn.

Core Maneuvers:

Maneuver	Effect
Move	Move up to Basic Move; no attack
Attack	One attack at full skill; can move ½ Basic Move
All-Out Attack (Determined)	+4 to hit; no active defenses this turn
All-Out Attack (Double)	Two attacks; no active defenses
All-Out Attack (Strong)	+2 damage or +1 per die; no active defenses
All-Out Defense	+2 to one active defense; can defend against all attacks
Defensive Attack	−2 to attack; +1 active defense
Wait	Hold action for trigger condition
Feint	Contested Quick Contest vs. opponent's combat skill — reduces opponent's next defense
Move and Attack	Move full speed, attack at −4; maximum skill 9

Active Defenses (the heart of GURPS combat):

Every attack that hits allows the defender to attempt one active defense:

Dodge: Basic Speed + 3, rounded down. Universal, works vs. all attacks.
Parry: ½ weapon skill + 3, rounded down. Only vs. melee attacks (some weapons).
Block: ½ Shield skill + 3, rounded down. Only with a shield or cloak.

These are rolled against on 3d6 roll-under. The attacker first rolls to hit; if they succeed, the defender rolls their defense. Both rolls are probabilistic. This creates a two-stage success system that is the most critical mechanic to translate to real-time.

Hit Locations (optional but critical for ARPG depth):

Location	Penalty to Hit	Effect
Torso	0	Standard damage
Skull	−7	×4 damage for crushing; knockdown at any injury
Face	−5	×1.5 crushing; bleeding; blind on critical
Neck	−5	×1.5 all damage; choke on critical
Eye	−9	Blind on any injury; ×4 effective
Arm	−2	Cripple on ≥ ½ HP to arm; drop weapon
Hand	−4	Cripple on ≥ HP/3
Leg	−2	Cripple on ≥ ½ HP to leg; fall
Foot	−4	Cripple; fall
Vitals	−3	×3 for impaling/piercing; ×1.5 tight-beam burn
Groin	−3	×1.5 for crushing; knockdown roll

Wound Modifiers by Damage Type:

This is GURPS's most sophisticated contribution to damage modeling:

Damage Type	Wound Multiplier	Notes
Small Piercing (spi)	×0.5	Tiny bullets, needles
Piercing (pi)	×1	Standard bullets, arrows
Large Piercing (pi+)	×1.5	Large caliber
Huge Piercing (pi++)	×2	Shotgun
Cutting (cut)	×1.5	Swords, axes — bleed risk
Impaling (imp)	×2	Spears, rapiers — double vs. torso
Crushing (cr)	×1	Blunt — best for knockdown
Burning (burn)	×1	Fire, energy
Tight-beam Burning	×1	Lasers; +×3 vs. vitals
Corrosion (cor)	×1	Acid — destroys armor
Toxic (tox)	×1	Disease, poison
Fatigue (fat)	×1	Non-injurious exhaustion

Example: A rapier does Thrust+2 impaling. At ST 12, thrust is 1d-1. Against a torso (vitals −3 to hit): 1d-1+2 = 1d+1, then ×2 for impaling = up to 14 penetrating damage. If the target has 10 HP, they're instantly incapacitated.

Knockdown and Stun: Any injury of HP/2 or more forces a HT roll or the target is knocked down (stunned, prone). This creates dramatic combat moments where a single good hit changes the fight.

1.8 Magic Systems

GURPS offers several magic systems, each with different feel:

GURPS Magic (Spell List Magic):

400+ individual spells organized into colleges (Fire, Water, Illusion, Necromancy, etc.)
Each spell is a Hard or Very Hard IQ-based skill
Casting costs Fatigue Points (FP); overcast risks FP collapse
Spells have maintenance costs for ongoing effects
Learning prerequisite spells is required (spell trees)
Maps well to skill tree progression for an ARPG caster archetype

GURPS Thaumatology (Alternative Magic Frameworks):

Ritual Path Magic — Ritual components, time investment, powerful but slow. Excellent for "witch doctor" pirate archetype preparing before battle.
Syntactic Magic — Combine verb+noun words of power for flexible effects. Perfect for a "sea-speech" magical language system.
Symbol Magic — Draw power from written symbols. Could become the "tattoo magic" system for cursed pirates.
Threshold-Limited Magic — Each caster has a personal Threshold of magical energy. Exceed it and catastrophic "mana overflow" occurs. Very relevant for a game about supernatural sea curses.
Chi Powers (from GURPS Martial Arts) — Internal power that enhances physical combat, no supernatural source required.

GURPS Horror / Powers — Curse Framework:

GURPS Horror details Afflictions (curse-like disadvantages applied by magic or monsters)
GURPS Powers provides a unified framework for supernatural abilities including psionic powers, innate attacks, and transformed/cursed characters
The Powers framework uses the concept of "Power Modifiers" that reduce or restrict ability costs — a cursed pirate's powers might have the Supernatural Origin modifier, making them detectable and suppressible by warding magic

1.9 Technology Levels

GURPS uses Technology Levels (TL) to classify gear and societies. Age of sail / Golden Age of Piracy is:

TL5 (Mass Production): 1450–1730. Matchlock and wheel-lock firearms. Cannon with black powder. Full plate armor declining, leather and buff coats rising. Square-rigged sailing ships.
TL5+1 or TL6 (Industrial Revolution): 1730–1880. Flintlock then percussion cap firearms. Rifled barrels. Iron-hulled ships beginning. More reliable cannon.

Salt & Steel's setting maps cleanly to TL5–TL6 transition — the classic Caribbean/Atlantic piracy era where flintlock pistols and cutlasses coexist. GURPS Low-Tech (2010) provides exhaustive period-accurate weapon and armor statistics.

TL5 Weapons from GURPS Low-Tech relevant to pirates:

Weapon	Damage	Notes
Cutlass	sw+1 cut or thr+1 imp	The quintessential pirate blade
Rapier	thr+1 imp	Dueling weapon; Weapon Master synergy
Boarding Axe	sw+2 cut or thr imp	Versatile shipboard tool/weapon
Flintlock Pistol	2d pi	Reload: 15 turns; Malf 16
Blunderbuss	1d+2 pi+	Cone; close range; pirate classic
Musket	4d pi	Long range; bayonet attachment
Belaying Pin	thr cr	Improvised, always available aboard ship
Hand Cannon	5d pi	Heavy; two-hands; devastating
Boarding Pike	thr+2 imp	Reach 1-2; excellent vs. unarmored

1.10 GURPS Martial Arts

GURPS Martial Arts (2008) is the most combat-focused supplement in the GURPS library. Key contributions:

Techniques: Individual combat maneuvers purchased at reduced point cost once you have the underlying skill. Examples:

Targeted Attack (Sword/Neck): Pay points to reduce the usual −5 penalty for neck strikes
Aggressive Parry: Counter-damage when parrying
Dual-Weapon Attack: Coordinated two-weapon attacks

Fighting Styles: Templates of skills, techniques, and advantages that define a combat style. For Salt & Steel, styles like "Caribbean Cutlass Fighting," "Naval Pistoleer," or "Corsair Grappling" could be pre-built templates players select or build toward.

Chi Powers and Trained by a Master: Allow superhuman physical feats within a realistic framework — perfect for the high-cinematic tone Salt & Steel needs (PoE characters do superhuman things without supernatural explanation).

2. GURPS Supplements Relevant to a Pirate ARPG

2.1 GURPS Swashbucklers (3rd Ed; no 4e equivalent — use with conversion)

The canonical pirate supplement. Covers:

Detailed ship types (sloop, brigantine, galleon, man-o-war) with GURPS stats
Crew quality and morale mechanics
Boarding action rules
Pirate codes, Brethren of the Coast, historical factions
Swashbuckling cinematic rules (chandelier swings, rope grabs, dramatic entrances)
Reputation mechanics for pirates (infamous vs. celebrated)
Tropic disease, scurvy, tropical storm hazards
Prize rules and plunder division

Direct Salt & Steel Mapping:

Ship type stats → Salt & Steel's ship chassis system
Crew quality tables → crew recruitment/progression
Boarding action rules → the "boarding encounter" combat mode
Reputation rules → faction standing system

2.2 GURPS Low-Tech (2010, 4th Ed)

The definitive guide to pre-industrial technology. Critical for Salt & Steel:

Full TL5 weapon statistics with consistent damage formulas
Armor statistics for buff coats, leather, breastplates
Sailing ship design rules
Navigation methods (dead reckoning, celestial navigation)
Knots, rigging, seamanship tools
Food preservation, water rationing at sea
Wound treatment (surgery, infection risk) before antibiotics

2.3 GURPS Action (2012, 4th Ed)

Designed for cinematic action-adventure. Key rules:

Wildcard Skills: "Guns!," "Sailor!," "Fight!" — broad-domain skills for fast-play
Impulse Buys: Spend character points during play for dramatic effect (never miss, never die, succeed on impossible task)
Action Point pacing for fast combat resolution
Simplified vehicle rules

For Salt & Steel: The Wildcard Skill system is the foundation of the Skill Atlas archetype paths. A player building a "Pistoleer" archetype might unlock the "Guns!" wildcard as a keystone node.

2.4 GURPS Magic (2004, 4th Ed)

400+ spells across 20 colleges. Most relevant colleges for pirate ARPG:

College	Pirate Application
Water	Sea control, storm summoning, currents, breathing water
Air	Wind conjuration (ship propulsion), lightning, fog
Fire	Weapon fire, burning pitch, cannon enhancement
Necromancy	Undead crew, ghost ships, curses, death ward
Illusion	Fog of war, false colors, phantom ships
Protection	Warding, sealing hulls, binding spirits
Earth	Stone ships, coral fortresses, island raising
Body Control	Curse of the sea, transformation, mermaid kin
Mind Control	Crew loyalty spells, siren song analog
Communication	Far-sight, message in a bottle, dead speech

2.5 GURPS Thaumatology (2010, 4th Ed)

Provides alternative magic frameworks and meta-rules for designing custom magic systems. The Threshold Magic system from Thaumatology is particularly relevant:

Each caster has a personal Threshold (e.g., 30 points of magical energy)
Casting spells drains from the Threshold
The Threshold recovers over time (one point/hour, or specific conditions)
Exceeding the Threshold causes "Overload" — roll on a surge table for catastrophic effects
This is a direct mechanical analog for "mana with dangerous overflow" that would suit a game about supernatural curses

2.6 GURPS Horror (2nd Ed 4e compatible)

Fright Checks: Exposure to horrific things forces a Will roll; failure causes mental trauma
Madness system: Accumulated failures produce long-term mental disadvantages
Curse mechanics: Detailed rules for applying curse-as-affliction, breaking curses
Undead stat blocks: Skeletons, ghosts, drowned dead — ready for Salt & Steel's enemy roster
The Rule of 16: In Horror, any spell or power at skill 16+ treats the roll as 16 for critical success purposes, preventing supernatural entities from being too reliably dominant

For Salt & Steel: The Fright Check system translates directly to a "Dread" mechanic — prolonged exposure to the supernatural accumulates dread that impairs combat and judgment.

2.7 GURPS Powers (2005, 4th Ed)

The unified framework for all non-magical supernormal abilities. Relevant to Salt & Steel's "cursed pirate" archetypes:

Power Modifiers: Every power belongs to a source (Psionic, Divine, Corruption, Sea-Born) that applies blanket modifiers
Advantages as Powers: Any GURPS advantage can be packaged as a Power with modified costs
Innate Attack: A flexible framework for unusual damage (acid spit, shadow bolt, cannonball-like impact)
Affliction: Framework for applying conditions, curses, and debuffs as attack modes

Salt & Steel Application: Cursed pirate abilities (ghostly phasing, davy jones strength, barnacle armor, water breathing) are all buildable as Powers with a "Corruption" power modifier (−10% cost, but detectable/suppressible by holy water/church magic).

2.8 GURPS Mass Combat (2000, converted to 4e)

Rules for battles involving hundreds or thousands of combatants. Most relevant:

Troop quality ratings translate crew competence
Commander's Leadership and Strategy skills matter
Force composition (ranged vs. melee vs. support) creates tactical decisions
Victory conditions and casualty calculations

For Salt & Steel: Mass Combat provides the framework for fleet battles when the player commands multiple ships. A simplified version where the player's individual GURPS-resolution combat affects the Mass Combat outcome creates the PoE-style "one badass hero changes the battle" fantasy.

First-class treatment of social mechanics as a system parallel to combat:

Influence Rolls: Reaction-based skill contests for social encounters
Status and Reputation: Quantified social standing that affects reaction modifiers
Contacts and Allies: Point-buy relationships
Group Reaction: Crowds and organizations have their own reaction patterns
Negotiation, Fast-Talk, Intimidation, Diplomacy as distinct skills with distinct mechanical outcomes

For Salt & Steel: Every faction (East India Company, Pirate Brethren, Spanish Crown, Voodoo Queen's Network) has a Reaction Table. The player's reputation score with each faction directly modifies all social rolls when dealing with them. This is more mechanically robust than PoE's reputation tiers because the modifier scale is continuous (not bucketed).

3. Adapting GURPS for Real-Time ARPG

This section is the core translation challenge. GURPS is a 1-second-turn simultaneous-declaration tabletop system. Salt & Steel is a real-time action RPG with tens of enemies on screen. Direct port is impossible; principled adaptation is not only possible but essential.

3.1 The 3d6 Bell Curve in Real-Time Combat

The Core Problem: GURPS relies on player and GM rolling dice explicitly each turn. Real-time combat requires the engine to make hundreds of hidden rolls per second.

The Solution: Invisible Dice as Engine State

The 3d6 roll-under is a probability function. The game engine can call this function for every attack resolution: success = roll3d6() <= skill_level. The player never sees the dice, but the probability distribution they've designed their character around governs all outcomes.

Practical Implementation:

function resolve_attack(attacker, defender, weapon):
    # Step 1: Attack roll
    attack_skill = attacker.get_weapon_skill(weapon)
    attack_roll = roll3d6()
    attack_hits = attack_roll <= attack_skill
    
    if not attack_hits:
        return MISS
    
    attack_margin = attack_skill - attack_roll  # used for special effects
    
    # Step 2: Active defense
    defense_type = defender.choose_best_defense(attacker, weapon)
    defense_value = defender.get_defense(defense_type)
    defense_roll = roll3d6()
    defense_succeeds = defense_roll <= defense_value
    
    if defense_succeeds:
        return DEFENDED
    
    # Step 3: Damage
    raw_damage = weapon.roll_damage()
    wound_modifier = weapon.get_wound_modifier(hit_location)
    penetrating = max(0, raw_damage - defender.get_DR(hit_location))
    final_damage = penetrating * wound_modifier
    
    # Step 4: Knockdown check if damage >= HP/2
    if final_damage >= defender.HP / 2:
        ht_roll = roll3d6()
        if ht_roll > defender.HT:
            defender.apply_knockdown()
    
    return HIT, final_damage

This function runs in microseconds. The bell curve distribution is "baked in" by the probability of roll3d6(). The player sees smooth real-time combat; the engine is doing turn-based GURPS resolution at 60fps.

The Feel Difference: With a d20 system (flat distribution), a character with 75% hit chance misses 1 in 4 attacks — and occasionally has a string of 5 misses in a row (probability ~0.1%). With 3d6 at skill 13 (62.5%), similar average results but streaks are dramatically rarer. A skilled pirate feels skilled. An unskilled enemy feels inconsistent. The bell curve makes character builds matter more consistently.

3.2 Point-Buy as a Skill Atlas

Conceptual Translation:

GURPS Concept	Salt & Steel Atlas Equivalent
Character Points	Skill Points (earned by leveling, completing challenges)
Attribute purchase	Attribute nodes on the Atlas (expensive, high-multiplier)
Skill purchase	Skill nodes in domain clusters
Advantage purchase	Passive nodes and Keystone nodes
Disadvantage acceptance	Burden nodes (optional, grant bonus points)
Wildcard skill	Archetype Keystone (broad domain mastery)
Point cost per level	Node cost in Skill Points

Atlas Architecture:

The Skill Atlas has five major regions corresponding to GURPS skill categories adapted for a pirate setting:

The Blade Coast (Combat cluster) — Sword, Shield, Brawling, Wrestling, Thrown Weapon, Fast-Draw, tactics
The Crow's Nest (Seamanship cluster) — Navigation, Seamanship, Meteorology, Knot-Tying, Ship Handling
The Tide Caller's Circle (Arcane cluster) — Spell colleges, occult knowledge, curse lore, ritual
The Merchant's Tongue (Social cluster) — Fast-Talk, Intimidation, Merchant, Savoir-Faire (Pirate), Leadership, Carousing
The Survival Shoal (Exploration/Survival cluster) — Swimming, Climbing, Stealth, Traps, First Aid, Fishing, Tracking

Point Cost Scaling:

Minor nodes: 1 point (small stat increase, +1 to specific roll)
Standard nodes: 2 points (skill level increase, minor advantage component)
Major nodes: 4 points (significant advantage, -1 to enemy defense)
Keystone nodes: 8–15 points (Wildcard skill, full Advantage, build-altering effect)

This mirrors GURPS's cost structure exactly while appearing as a visual spatial tree.

3.3 Active Defenses as Real-Time Mechanics

The Central Insight: GURPS active defenses are already the thing ARPGs want — a meaningful choice between dodge, parry, and block rather than passive mitigation.

Real-Time Implementation Options:

Option A: Player-Triggered Defense Window

Attack animations have a telegraph phase (visual/audio cue)
Player presses a defense button during the window
Which button pressed determines defense type (dodge roll, weapon parry, shield block)
Engine runs the GURPS defense roll behind the scenes
The character's defense value determines the probability of the roll succeeding
High Dodge stat = dodge button more reliable; high Shield skill = block button more reliable
"Git gud" skill + character build both matter

Option B: Auto-Defense with Resource Cost

Each defense type has a cooldown or resource cost
Dodge uses FP (GURPS fatigue)
Parry can be used freely but reduces that weapon's attack on the next turn
Block costs nothing but requires shield equipped
Character build determines how often each can be used and how reliable each is

Option C: Hybrid (Recommended)

All-Out Attack stance: character automatically uses no active defense; gains significant offensive bonus
Normal stance: player can trigger dodge (using FP) or the character auto-parries/auto-blocks with their equipped items at their built defense values
All-Out Defense stance: no attacks; double defense rolls or guaranteed success on defense at the cost of tempo

This maps GURPS maneuvers (All-Out Attack, All-Out Defense, Defensive Attack) directly to real-time stances while preserving the mechanical meaning.

3.4 Skill Levels as Visible Power Progression

GURPS skill levels produce nonlinear probability jumps that feel meaningful at every step. This is the "aha moment" for how to make skill progression satisfying in Salt & Steel:

Sword Skill Progression Feel:

Skill Level	Hit% vs. Dodge 10	What it Feels Like
9 (untrained)	~14%	Barely scratch them; embarrassing
11	~33%	Land hits occasionally; still unreliable
13	~55%	More hits than misses; starting to feel capable
15	~72%	Dependable fighter; rarely miss skilled opponents
17	~84%	Expert level; misses are surprises
19 (master)	~92%	Near-perfect; only bad luck defeats you

The bell curve creates these nonlinear jumps. Going from skill 9 to 11 feels much more powerful than the numbers suggest because you're climbing the steep part of the bell curve. Going from 17 to 19 is expensive and provides less felt improvement — accurately reflecting that mastery is costly and its gains are marginal.

ARPG Visualization: Skill level could be displayed as a star rating (1–10 stars, corresponding to effective skill 8–22), with visible "mastery milestones" at skills 12, 15, 18, and 20 that unlock new techniques/animations.

3.5 Advantages as Build-Defining Keystones

GURPS advantages map exactly to PoE keystone passives — traits that fundamentally change how a build plays.

Proposed Salt & Steel Keystones from GURPS Advantages:

GURPS Advantage	Salt & Steel Keystone	Gameplay Effect
Combat Reflexes	"Powder-Quick Reflexes"	Cannot be surprised; +1 all defenses; auto-succeed on initiative
Weapon Master (Blades)	"Blade Saint"	All blade parries at ½+3; blade skill up to 2× normal cap
Extra Attack 1	"Twin Strikes"	One additional attack per action window
Danger Sense	"Sea Witch's Warning"	3-second warning before ambushes; UI alert on screen
Luck	"Buccaneer's Fortune"	Once per minute, any roll may be re-rolled; take the better
High Pain Threshold	"Iron Constitution"	Ignore wound penalties; no stun from non-critical hits
Gunslinger	"Dead Eye"	No accuracy penalty for shooting from movement; pistol reload in half time
Perfect Balance	"Sea Legs"	Immune to knockback/knockdown; no ship-sway penalty
Ambidexterity	"Two-Fisted Devil"	No off-hand penalties; full dual-wield capability
Trained by a Master	"Fighting Master"	Unlocks Techniques (special attacks) for equipped weapon type
Fearlessness 3	"Davy Jones' Nerve"	Immune to Dread accumulation; resist Fright Checks

Anti-Keystones from GURPS Disadvantages (optional Burden nodes):

GURPS Disadvantage	Salt & Steel Burden	Points Gained	Gameplay Effect
Cursed	"The Mark of Davy Jones"	15 pts	Random catastrophic events (ship damage, weapon breaking, rope snapping) every 10–15 minutes real time
One Eye	"Glass Eye"	5 pts	−1 ranged attacks; −1 Per-based rolls
Bloodlust	"Seeing Red"	5 pts	Cannot accept surrender; must kill downed enemies
Greed	"Gold-Sickness"	5 pts	Self-control roll (HT check) to leave treasure unlooted
Dependency (rum)	"The Bottle"	5 pts	FP regeneration halved unless rum consumed recently
Unluckiness	"Snake Eyes"	5 pts	Once per 10 minutes, a random roll becomes its worst result

3.6 Hit Locations in an ARPG

Approach A: Targeted Attacks

Player holds a modifier key and directional input to designate a hit location
Penalty to attack roll equal to GURPS hit location penalty
Reward: damage multiplier and special effect if penetrating damage lands
Example: targeting leg (−2 attack) on kill applies "Cripple" debuff; target stumbles

Approach B: Stance/Skill-Based Location

Certain weapon techniques target specific locations automatically
"Death from Above" technique always targets skull (−7 but ×4 damage)
"Hamstring" technique always targets leg (−2; cripple on penetrating)
Player chooses the technique; engine resolves location targeting

Approach C: Enemy Weak Points (Recommended for base game)

Enemies have visible weak point zones (glowing joints on undead, powder keg on a soldier's belt)
Targeting these is a skill-check: base 0 to −5 penalty, with bonus damage
Player aims cursor/attack direction toward the zone; engine applies location rules
Weapon type matters: impaling vs. vitals does ×6 total (×2 impaling × ×3 vitals location modifier)

3.7 Fatigue Points as Action Resource

GURPS Fatigue Points (FP) are the most direct analog for an action economy resource in real-time play. FP depletes from:

Physical exertion (running, fighting)
Casting spells (each spell costs FP)
Certain environmental effects (extreme heat, cold)
Injury to the point where HP goes negative

FP recovery: 1 FP per 10 minutes of rest (base). Advantages like Fit or Very Fit accelerate this.

Salt & Steel FP Implementation:

FP serves as the unified action resource — replacing both traditional stamina and mana:

Dodge rolls: cost 1 FP per dodge (discourages infinite evasion)
Power attacks: cost 1 FP for All-Out Attack variant
Spells: cost FP as in GURPS Magic (simple cantrips 1 FP; major spells 5-10 FP)
Sprinting: cost 1 FP per 10 seconds
Active defense chain: Third+ active defense in 3 seconds costs 1 FP each

FP floor effects (from GURPS Basic Set):

FP ≤ 1/3 max: Move and Dodge halved
FP = 0: Unconsciousness check each turn (HT roll)
FP below 0: 1 HP lost per FP below 0 (dangerous)

This makes FP management a meaningful skill in sustained fight sequences — a PoE-style "how long can I sustain this encounter" tension.

3.8 Reaction Rolls as Faction Reputation

GURPS reaction rolls (2d6 roll-high on a scale from −6 Very Bad to +6 Very Good) determine NPC disposition. The base roll is modified by:

Status (social class/rank modifier)
Reputation (explicit reputation modifiers for specific groups)
Appearance
Relevant advantages (Voice, Charisma)
Relevant disadvantages (Odious Personal Habit, Social Stigma)

Salt & Steel Translation:

Each major faction has a Reaction Score from −6 to +6 that the player accumulates through actions. This score directly modifies all social rolls (Fast-Talk, Intimidation, Merchant) when dealing with that faction's members.

Faction Reaction Table:

Score	Reaction	Effect
+6	Worshipful Ally	Free goods, safe harbor, crew volunteers freely
+4 to +5	Good Friend	Discounts, information willingly shared, hired crew loyal
+2 to +3	Friendly	Normal commerce; some favors available
0 to +1	Neutral	Standard prices; no favors; no hostility
−1 to −2	Unfriendly	Worse prices; rumors spread; some refuse service
−3 to −4	Bad	Crew won't sign on; port authorities watch you
−5 to −6	Hostile	Attacked on sight; bounty placed; enemies patrol

This produces a continuous, meaningful social simulation rather than simple "friendly/neutral/hostile" buckets.

4. What GURPS Provides That PoE Doesn't

4.1 Realistic Damage Modeling

PoE uses elemental damage types (Fire, Cold, Lightning, Physical, Chaos) primarily as resistances and thematic triggers. The actual wound mechanics are flat damage-minus-armor.

GURPS's wound modifier system creates weapon identity at a mechanical level:

A rapier (impaling, ×2) is genuinely better against unarmored enemies but struggles against heavy armor
A cutlass (cutting, ×1.5) is the all-around choice and bleeds enemies
A boarding axe (swing cutting + thrust impaling) is versatile
A flintlock (large piercing, ×1.5) is devastating but has catastrophic reload timing
A belaying pin (crushing, ×1) is worst for damage but best for non-lethal knockdown

This creates weapon choice with actual mechanical consequences, not just different names for the same damage formula.

4.2 Advantage/Disadvantage Character Definition

PoE builds are defined primarily by passive stat accumulation and item affixes. Character identity comes from skill gems and ascendancies.

GURPS advantages/disadvantages define who the character is, not just what they can do. A character with:

Danger Sense + Luck + Fearlessness = the impossibly lucky survivor type
Bloodlust + High Pain Threshold + Berserk = the terrifying berserker
Empathy + Charisma + Voice = the crew-inspiring leader
Cursed + Extraordinary Luck (disadvantage offset by advantage) = the character the universe both hates and protects

These are character concepts, not just stat configurations. This is the distinction Salt & Steel needs to feel like more than PoE-with-pirates.

PoE has almost no social system — NPCs exist to give quests and sell items. GURPS Social Engineering makes social encounters as mechanically rich as combat:

Negotiations have rolls and margins of success
Failing a social roll has consequences (price increases, reputation damage, physical threat escalation)
Different skills work better with different NPCs in different situations
Leadership and crew morale are tracked mechanics

A Salt & Steel player who builds into social skills should have genuinely different gameplay — not just unlocking flavor dialogue but accessing different missions, better prices, more loyal crew, intelligence on enemy positions.

4.4 Explicit Technology Level Framework

PoE's gear system is essentially timeless — items from different "eras" exist in the same pool. GURPS's TL framework provides:

Natural gear progression from TL4 (cutlasses, matchlocks) through TL5 (flintlocks, proper rigged ships) to TL6 (percussion caps, early rifling)
Each TL represents both historical period and power level
Gear from higher TLs provides measurable advantages that justify acquisition
The framework prevents "why would I use this old sword" — everything has its TL-appropriate niche

For Salt & Steel: TL serves as a secondary item tier system. A TL5 flintlock pistol has different reload time, malfunction range, and damage than a TL6 percussion revolver. Finding and upgrading to higher-TL versions is meaningful progression distinct from magical enhancement.

4.5 Fatigue and Encumbrance as Meaningful Mechanics

PoE abandoned encumbrance entirely. GURPS makes it a central system:

Carrying too much loot degrades Dodge and Move
Players must make genuine choices about what to carry
Heavy armor reduces encumbrance capacity, creating the armor tradeoff
FP depletion in combat is a loss condition short of death — you can be exhausted into incapacity

These mechanics create resource management tension that makes exploration meaningful beyond "find enemies, kill enemies, loot everything."

4.6 Detailed Grappling and Martial Arts

PoE's grappling is nonexistent. GURPS Martial Arts provides:

Full grapple/hold/throw/pin system with dedicated mechanics
Each wrestling action (grab, joint lock, choke, throw) has distinct outcomes
Boarding an enemy ship involves grappling with an enemy crew — these rules matter
Grappling while on a ship deck in rough seas uses both Wrestling and Seamanship

A Salt & Steel grappling archetype (Wrestling + Brawling + Strength) would be mechanically complete and distinct from pure weapon combat.

4.7 Mass Combat for Fleet and Crew

PoE is exclusively personal-scale combat. GURPS Mass Combat allows zooming out to fleet-level:

The player's personal combat skill contributes to Mass Combat as a "hero unit" bonus
Commander's Leadership affects troop morale
Tactical decisions (flanking, holding ground, artillery priority) matter at fleet scale
Individual ship vs. fleet engagement has clear mechanical rules

For Salt & Steel's Endgame: Fleet battles where the player commands multiple ships, fights personally on their flagship, and sees the Mass Combat results of their personal combat excellence is a uniquely GURPS-enabled experience.

4.8 The Wildcard Skill Concept

GURPS Action's Wildcard skills are broad-domain expertise packages. "Guns!" covers all gunpowder weapons. "Sailor!" covers all seafaring tasks. "Fight!" covers all unarmed and armed melee.

For Salt & Steel, Wildcard skills enable a late-game "generalist mastery" fantasy:

Spending heavily on a Wildcard means the character is reliably excellent across an entire domain
This creates a meaningful alternative to deep specialization
A player with "Sailor!" + "Fight!" + "Guns!" is a complete pirate archetype — the classic adventurer who can do it all

4.9 Mental Advantages/Disadvantages as Unique Gameplay

Trait	Gameplay Mechanic
Danger Sense	UI shows incoming attacks 2-3 seconds early when it triggers
Intuition	Player gets hint text about optimal approaches to encounters
Empathy	Can read enemy morale state; see when enemies are about to flee
Precognition	(From GURPS Powers) Brief flashes of near-future state
Photographic Memory	All maps permanently revealed once visited; all NPC names remembered
Eidetic Memory	+4 to any skill roll when referencing something previously encountered
Claustrophobia	Disadvantage: panic in ship holds; must fight through penalty in close quarters
Thalassophobia	Disadvantage: enormous penalty when swimming or overboard

5. The Salt & Steel Attribute Model

5.1 Direct Mapping Proposal

ST — Strength

Melee damage dice (GURPS Thrust/Swing formula)
Basic Lift → carry capacity for loot and gear
Grappling effectiveness
Crew intimidation bonus (Reaction modifier for Intimidation rolls)
Boarding success modifier
Costs: 10 points/level (base 10)

DX — Dexterity

Default for all physical combat skills
Dodge value base component (Basic Speed → Dodge)
Ranged attack base (Guns, Bow, Thrown default to DX-based)
Ship handling in tight quarters
Pickpocketing, sleight of hand
Costs: 20 points/level (base 10) — most expensive primary

IQ — Intelligence

Default for all mental and social skills (Navigation, Tactics, Fast-Talk, Merchant)
Spell skill base for mages
Crafting insight bonus
Trap detection and device use
Ritual magic effectiveness
Costs: 20 points/level (base 10)

HT — Health

FP maximum (equals HT by default)
Knockdown/death resistance rolls
Disease and poison resistance
Curse resistance rolls (Will is the primary but HT is secondary)
Recovery speed from wounds
"Sea endurance" — rolls for surviving extreme weather, thirst, scurvy
Costs: 10 points/level (base 10)

5.2 Secondary Stats Implementation

HP (Hit Points = ST by default, buy separately at 2 pts/HP)

Primary survivability pool
Drop to 0: incapacitation risk (HT roll to stay conscious)
Drop to −HP: death check (HT roll to survive)
Drop to −5×HP: instant death (no roll)
For Salt & Steel: ×3 HP scaling at minimum to accommodate ARPG numbers (base game HP ~300-3000, scaling from GURPS's base ~10)

FP (Fatigue Points = HT by default, buy separately at 3 pts/FP)

Universal action resource (replaces mana, stamina, endurance)
Drains from: dodging, power attacks, spells, swimming, sprinting, extended combat
Recovery: slow out of combat, faster with rest, items, certain advantages
At ≤ 1/3 FP: Move and Dodge halved — visually show character becoming exhausted
At 0 FP: each further depletion costs 1 HP — life force being consumed

Will (= IQ by default, buy separately at 5 pts/level)

Fright Check resistance (horror/supernatural encounters)
Curse resistance (magical afflictions)
Mental disadvantage self-control rolls
Crew morale bolstering (Leadership supplement)

Per (Perception = IQ by default, buy separately at 5 pts/level)

Trap detection
Treasure sensing (proximity system — higher Per spots buried/hidden treasure from further)
Enemy detection (stealth vs. Per contest)
Weather prediction (Meteorology uses Per base)

Basic Speed = (DX + HT) / 4

Governs attack speed timing (faster Basic Speed = shorter attack animation lockout)
Initiative order in simultaneous-action resolution
Dodge value: Basic Speed + 3, rounded down
At Speed 7 (DX 14, HT 14): Dodge 10 — nearly impossible to hit reliably

Basic Move = Basic Speed, rounded down

Hex movement (maps to m/s movement speed)
Sprint speed = Basic Move × 1.2
Affects kiting distance, chase mechanics, boarding speed

5.3 Derived Formulas in Practice

Example character: "Claudette the Corsair"

ST 12, DX 14, IQ 11, HT 12
HP: 12 (= ST); FP: 12 (= HT); Will: 11 (= IQ); Per: 11 (= IQ)
Basic Speed: (14+12)/4 = 6.5; Basic Move: 6; Dodge: 9
Basic Lift: 144/5 = 28.8 lbs; encumbrance is real consideration
Sword skill (DX-based, Average): at DX 14, spending 2 pts = skill 14 → 90.7% base hit
Attribute costs: ST 20 + DX 80 + IQ 10 + HT 20 = 130 points before skills/advantages
This is a 200-point character budget — standard for cinematic heroes

6. The GURPS-Inspired Skill Atlas

6.1 Architecture Overview

The Skill Atlas is the visual, spatial representation of GURPS's point-buy system. It is a map of interconnected nodes, each representing a GURPS point investment. The player allocates Skill Points (earned through experience) by navigating the Atlas from their starting position.

Atlas Topology:

Five major region clusters (see Section 3.2)
Clusters connect via "cross-training corridors" — nodes that bridge two domains
Center of the Atlas: Universal nodes (HP, FP, Will, Per — the secondary stats)
Edges of the Atlas: Keystone nodes (the most powerful, domain-specializing effects)

6.2 Node Types

Stat Nodes (1–4 points):

+1 to a skill level
+1 HP or FP
+1 Will or Per
Small attribute fractions (toward next attribute level)

Technique Nodes (2–4 points):

Reduce penalty for a specific technique (Targeted Attack, Dual-Weapon Attack)
Unlock a new combat maneuver variant
Add a secondary effect to an existing skill

Advantage Nodes (4–15 points):

Implement a GURPS advantage as a single purchase
High Pain Threshold: 10 pts
Combat Reflexes: 15 pts
Danger Sense: 15 pts

Keystone Nodes (8–45 points, special prerequisites):

Wildcard skills ("Guns!," "Sailor!," "Fight!")
Multi-level advantages (Weapon Master, Extra Attack, Trained by a Master)
Build-defining passives that change core mechanics

Burden Nodes (negative, generate points):

Optional negative keystones
Player must path through and activate them (opt-in)
Cannot be deactivated once taken (mirrors GURPS disadvantage permanence)
Provide extra points to allocate elsewhere

6.3 Region Design — The Blade Coast (Combat)

The Blade Coast is the central combat skill cluster, sub-divided into:

Melee Branch:

Brawling E (DX base) → Boxing A → Karate H
Shortsword A → Sword A → Two-Handed Sword A
Knife E → Main-Gauche A (parrying dagger)
Staff A → Spear A → Polearm A
Keystone: "Blade Saint" (Weapon Master — Blades, 45 pts)

Ranged Branch:

Guns (Pistol) E → Guns (Longarm) E → Guns (Artillery) A
Thrown Weapon (Knife) E → Thrown Weapon (Explosive) A
Crossbow E → Bow A
Keystone: "Dead Eye" (Gunslinger, 25 pts)

Defense Branch:

Shield E → enhanced Block
Parry Nodes: Enhanced Parry 1-3
Dodge Nodes: Enhanced Dodge 1-3
Keystone: "Untouchable" (Enhanced Dodge 3 + Enhanced Parry 3 — 60 pts total — no All-Out Attack available while this is active)

Technique Branch (requires Trained by a Master keystone):

Disarming
Feint
Targeted Attack (Neck)
Targeted Attack (Vitals)
Aggressive Parry
Dual-Weapon Attack

6.4 Region Design — The Crow's Nest (Seamanship)

Seamanship E → advanced ship tasks
Navigation (Sea) A → celestial navigation (IQ-based)
Meteorology A → weather prediction, storm avoidance
Knot-Tying E → rigging, capture, boarding operations
Sailing A → active ship control (emergency maneuvers)
Boatswain node cluster (crew management)
Keystone: "Master Mariner" (Wildcard: Sailor!, 24 pts at IQ 12 base)

6.5 Region Design — The Tide Caller's Circle (Arcane)

The Arcane region is the most complex, mirroring GURPS Magic's college system:

Each college has a cluster of spell nodes
Prerequisite spells must be purchased before advanced spells
The college nodes mirror GURPS's actual spell trees
Keystone: "Threshold Mage" (Threshold Magic system — doubles spell power but risks Overload on 3d6 ≥ Threshold roll)
Keystone: "Curse-Breaker" (enables ritual curse removal — requires Exorcism + Occultism + Thaumaturgy)
Cross-training corridor to Tide Caller from Crow's Nest: "Sea Speech" — the language of water spirits (Seamanship + Water college synergy)

Fast-Talk A (IQ-base) → Propaganda A → Brainwashing VH
Intimidation A (Will or ST, whichever is higher)
Merchant A → Streetwise A
Leadership A → Strategy H → Tactics H
Savoir-Faire (Pirate) E — reduces reaction penalties with pirate factions
Carousing E → Gambling A → Sleight of Hand A
Keystone: "Infamous Captain" (Reputation +4 with all pirate factions; −4 with all naval factions — net 0 pts but redistributes reaction modifiers dramatically)
Keystone: "The Voice" (Voice advantage 10 pts + Charisma 3 levels 15 pts — combined 25 pt keystone for social builds)

One critical design implication: because the 3d6 bell curve creates diminishing returns at high skill levels (going from 16 to 18 only improves success from 97.7% to 99.5%), the Atlas should make higher-level nodes increasingly expensive and increasingly provide qualitative changes rather than quantitative ones.

Skill Level → Node Cost Progression:

Skill Level	Points to Reach (Average skill)	Cost of Next Level
10 (default)	2	2 → 4
11	4	4
12	8	4
13	12	4
14	16	8
15	24	8
16	32	—

Going beyond 16 in GURPS requires special advantages (Weapon Master increases effective cap; Training allows 20+). In Salt & Steel, the Atlas's Keystone nodes should be the gateway to exceeding the "normal" skill cap — which is exactly how PoE's ascendancy keystones work.

7. Combat System Translation

7.1 Real-Time Maneuver Mapping

GURPS's per-turn maneuvers translate to real-time combat stances with different risk/reward profiles:

GURPS Maneuver	Salt & Steel Stance	Activation	Trade-off
Attack	Normal Stance	Default	Balanced offense/defense
All-Out Attack (Strong)	Reckless Strike	Hold attack button	+2 dmg/die; no defenses this window
All-Out Attack (Double)	Twin Fury	Double-tap attack	Two hits; no defenses; costs 1 FP
All-Out Attack (Determined)	Committed Strike	Directional + attack	+4 to hit; 1-second defense lockout
All-Out Defense	Guard Stance	Hold block/dodge	+2 all defenses; no attacks possible
Defensive Attack	Cautious Strike	Modifier + attack	−2 to hit; +1 all defenses during attack
Feint	Feint	Special input combo	Contested roll; reduces target's next defense
Wait	Anticipate	Hold button facing direction	Attack triggers automatically if enemy enters range
Move and Attack	Rush Attack	Sprint + attack	Full movement; −4 attack; max effective skill 9

7.2 Active Defense Real-Time Resolution

The Two-Second Window:

When a melee attack connects (attacker's roll ≤ skill), the defending player has a 300ms window (adjustable based on Basic Speed) to trigger an active defense. The window is communicated by:

Screen flash/tint
Audio cue
Attack animation at 75% completion

During that window, the player can:

Dodge (default): Triggers dodge animation; engine rolls 3d6 vs. Dodge value
Parry (weapon equipped): Triggers parry animation; engine rolls 3d6 vs. Parry value
Block (shield equipped): Triggers block animation; engine rolls 3d6 vs. Block value
Do nothing: Takes the hit directly

High-speed players with Combat Reflexes never miss the window. Players without Combat Reflexes can be surprised (miss the window on first attack from a new threat). The window is a real-time skill expression of the character's built defense values.

Rapid Fire Defense Degradation:

GURPS allows multiple defenses per second but with accumulating penalty. In Salt & Steel:

First defense in 2 seconds: no penalty
Second defense: −1 to defense roll
Third+ defense: −2 per additional defense
With All-Out Defense active: reset penalty; each defense is at +2

This creates the high-pressure multi-enemy situation where the player must choose which attacks to defend and which to eat — exactly the combat tension PoE 2 aims for.

7.3 Damage Type Differentiation as Weapon Identity

Instead of PoE's elemental damage types, Salt & Steel uses GURPS wound types as the primary damage taxonomy:

Cutting (swords, axes):

×1.5 wound multiplier
Causes bleeding (ongoing HP loss)
Best against lightly armored targets
Penalized by metal armor (DR cuts significantly)

Impaling (rapiers, boarding pikes, spears):

×2 wound multiplier
Does not cause bleeding but devastating penetrating wounds
Crits deal ×3 due to combined wound modifier on critical
Excellent vs. vitals (rapier vs. torso vitals: 2d+2 × ×2 × ×3 vitals = potential instant kills)

Crushing (blunt weapons, cannon blast, grapple):

×1 wound multiplier
Best for knockdown (HT roll threshold lowered)
Works against all armor types (no "too tough to crush")
Non-lethal takedowns easier with crushing

Piercing (firearms, arrows):

Small (×0.5): weak pistols, light arrows
Standard (×1): typical bullets
Large (×1.5): musket balls, heavy arrows
Huge (×2): blunderbuss, cannon grapeshot
Firearms are the "assassin" damage type — high per-shot but reload cost

Burning (explosions, alchemical fire):

×1 multiplier but ignites (ongoing burn, armor does not protect against the continuing fire)
Grenados and fire pots become tactically valuable

Corrosion (acid, certain sea creature attacks):

×1 multiplier
Permanently reduces armor DR (cannot be repaired without specific crafting)
Makes certain enemies "armor killers"

7.4 Firearms in Detail

GURPS handles firearms with detailed rules that create genuine tactical texture:

Flintlock Pistol (TL5):

Damage: 2d pi (large)
Acc: 2 (accuracy bonus for aiming)
Range: 20/200m (short/long)
Shots: 1 (1)
Reload: 15 turns (15 seconds — prohibitive in real-time)
Malfunction: 16 (rolls of 16-18 cause misfire — relevant on 3d6)
Weight: 2.6 lbs

In Salt & Steel Real-Time: Flintlock pistols become "execute" weapons:

Draw the pistol (free action with Quick-Draw skill)
Must aim for 2 seconds (Acc bonus only applies with 2+ seconds aim time)
Fire for devastating damage (2d pi+ = potentially 7-12 damage before wound modifier)
Spend 15 seconds reloading (during which the pistol is a club)
Or holster and draw a second pistol

This makes the "two pistol" loadout (from Dual Weapon Fighting) a genuine tactical decision — burning both shots for burst damage, then switching to blades.

The Gunslinger Advantage changes pistol combat fundamentally:

No aiming turns required for Acc bonus
No penalty for firing from combat movement
Reload time halved (due to Guns at 20+ skill)
This is the dedicated "pistoleer" keystone

7.5 Dual-Wielding (Cutlass and Main Gauche)

GURPS handles dual-wielding through the Dual-Weapon Attack rule:

Requires Ambidexterity advantage (5 pts) OR −2 penalty for off-hand
Each weapon attacks at full skill −2 (or −4 without Ambidexterity)
Can both attack the same target or split attacks
Each weapon parries separately (main-gauche has the Parry special property)
Main-gauche (parrying dagger) built for defense: lighter, faster, designed to catch blades

Salt & Steel Dual-Wield build:

Ambidexterity keystone (5 pts)
Two Weapon Fighting technique training (reduces dual penalty)
Main-Gauche skill at high level (parry-focused)
Sword skill at high level (attack-focused)
Combat Reflexes (defense bonus to both)
Result: aggressive high-attack with solid parrying backup

7.6 Grappling and Boarding Combat

GURPS Wrestling/Judo provides the foundation for boarding combat:

Grapple sequence:

Grabber rolls DX or Wrestling vs. target's Dodge
If grab succeeds, target is grappled (−4 DX; cannot dodge)
Subsequent turns: Grabber can attempt choke, pin, throw, or joint lock
Each contested by ST vs. ST (or Judo/Wrestling vs. opponent)
Pin: target helpless until escaped (escape roll: ST vs. ST or DX vs. ST)

Shipboard Grappling Context:

Moving targets on a ship deck (rough sea) adds Seamanship requirement or penalty
Grappling an enemy toward a railing allows a throw overboard (ST vs. ST + height advantage)
Boarding hooks and ropes are equipment that enables grappling between ships
A character with Wrestling 16+ can subdue most enemies without killing — relevant for taking prisoners/hostages

7.7 GURPS Rapid Strike and Extra Attack

Rapid Strike (from GURPS Basic Set):

Make two attacks at −3 each (or −6 each for less skilled)
Requires Technique: Rapid Strike to reduce penalties
Can target different locations or the same

Extra Attack Advantage:

Each level (25 pts/level) provides one additional attack per combat turn
Up to 4 Extra Attacks possible (prohibitively expensive at 100 pts but buildable)
In real-time: each Extra Attack level reduces the animation lockout between attacks by ~20%

Salt & Steel Attack Speed Progression:

Extra Attacks	Real-Time Effect	Atlas Cost
0	Normal attack cadence	—
1	30% faster repeat attacks	25 pts
2	55% faster; can chain 3-hit combos	50 pts
3	Near-continuous; 4-hit chains	75 pts
4	Blur of attacks; cap at physics	100 pts

Combined with Rapid Strike techniques, a character with Extra Attack 2 can potentially make 6 attacks in the time a normal character makes 2. This is the "Flurry of Blows" archetype that PoE and other ARPGs model but rarely ground in a rules system.

8. Probability Analysis: 3d6 vs. d20 vs. Percentile

8.1 3d6 Probability Distribution

The 3d6 distribution is normal-ish (bell curve approximation):

Roll	Probability	Cumulative (roll ≤ X)
3	0.46%	0.46%
4	1.39%	1.85%
5	2.78%	4.63%
6	4.63%	9.26%
7	6.94%	16.20%
8	9.72%	25.93%
9	11.57%	37.50%
10	12.50%	50.00%
11	12.50%	62.50%
12	11.57%	74.07%
13	9.72%	83.80%
14	6.94%	90.74%
15	4.63%	95.37%
16	2.78%	98.15%
17	1.39%	99.54%
18	0.46%	100.00%

Key Insight: The central values (9-12) appear much more often than extremes. Roll-under mechanics mean high skill levels (14-16) give reliably high success rates, while low skills (8-9) produce mostly failures. You cannot "luck into" success at the same rate as a flat distribution.

8.2 d20 Flat Distribution

A d20 produces exactly 5% probability per value. A skill of 75% (15/20) with a d20 will produce:

Exactly 5% chance of natural 20 (crit)
Exactly 5% chance of natural 1 (fumble)
Consistent 75% success rate regardless of whether you rolled 14 three times in a row

PoE's Effective System: PoE doesn't use raw d20. It uses a continuous probability roll (0-100) for most mechanics, making it effectively a flat percentile distribution. Hit chance, critical strike chance, and block chance are all flat percentile modifiers.

8.3 Critical Comparison for Salt & Steel

Property	3d6 Roll-Under (GURPS)	d20 (D&D style)	Flat % (PoE style)
Critical range	Skill-dependent	Fixed 5%	Fixed % (configurable)
Fumble range	Skill-dependent	Fixed 5%	Fixed % or zero
Streak resistance	High (bell curve)	Low (flat)	Low (flat)
Feel at high skill	Reliably excellent	Same as low skill on extremes	Reliably excellent
Feel at low skill	Mostly misses	Still 5% crit	Mostly misses
Mathematical complexity	Moderate	Low	Low
Intuitive for players	Initially confusing	Immediately understood	Immediately understood

Recommendation for Salt & Steel:

Use 3d6 for all character-driven rolls (attack, defense, skill checks, curse resistance). Use flat % for item-driven properties (item quality chance, loot rarity, enchantment success). This creates a two-layer system:

Character build reliability comes from the bell curve (your character is as good as their stats consistently)
Item system excitement comes from flat % (those 5% drop chances feel like lottery luck)

This mirrors how GURPS handles the distinction: character stats use 3d6; equipment quality is fixed.

8.4 Critical Success and Failure Probabilities

GURPS Critical Success Rules:

Roll ≤ 4: Always critical (0.46% base, ignoring skill)
Roll ≤ skill−10: Critical (only relevant at skill 14+; skill 14 crits on rolls ≤ 4 which is identical)
At skill 15: crits on ≤ 5 (4.63%)
At skill 16: crits on ≤ 6 (9.26%)
At skill 20: crits on ≤ 10 (50%)

This is radical: At extremely high skill, critical success becomes the norm. A character with Sword-20 crits half the time. This is not a flaw; it is the design intent. Mastery means mastery.

Salt & Steel Crit Implementation:

Map GURPS critical ranges to Salt & Steel visual feedback:

Normal success: Standard hit animation + damage
Critical success: Enhanced animation, bonus damage multiplier, possible special effect (bleed, stun, knock prone)
Critical failure: Dramatic failure animation (weapon drop, self-stumble, shot goes wild)

The variable crit rate based on skill (not item affixes alone) is the key differentiator from PoE.

9. Recommended Design Decisions

9.1 Core Engine: Full 3d6 Resolution

Adopt GURPS's 3d6 roll-under as the combat resolution engine. Every attack roll, defense roll, skill check, and curse resistance roll uses roll3d6() <= stat. This is non-negotiable for preserving the feel of character build mattering.

The engine runs this resolution at 60fps invisibly. Players see outcomes; designers tune probabilities by tuning stats.

9.2 Attribute System: All Four Primary Stats

Adopt ST, DX, IQ, HT with GURPS's exact point costs scaled to the game's budget. A starting character budget of approximately 150 points with 50 additional points awarded through the first 20 levels provides enough to build a focused archetype while leaving room for expansion.

Scaling: Multiply all HP/FP/damage numbers by 10 for ARPG feel (Salt & Steel base HP ~100-120 rather than GURPS's 10-12), but keep the underlying ratios identical. The 3d6 rolls don't care about HP scale.

9.3 FP as the Universal Action Resource

Replace all stamina/mana/energy systems with a single FP pool. FP management is Salt & Steel's primary resource game:

FP regenerates slowly in combat (1 FP per 3 seconds of non-exertion)
FP regenerates quickly out of combat (1 FP per 5 seconds)
FP-extending items and advantages are the equivalent of PoE's "mana regeneration" build axis
A character with 30 FP can do far more before exhaustion than one with 12 FP — build decision

9.4 Skill Atlas as PoE-Style Passive Tree

Build the Skill Atlas as described in Section 6. Use GURPS point costs as node costs. The five regional clusters map to five character archetypes:

Blade Coast → Corsair (melee fighter)
Crow's Nest → Navigator (utility/support)
Tide Caller → Sea Witch (caster)
Merchant's Tongue → Buccaneer (social/hybrid)
Survival Shoal → Ghost (stealth/explorer)

Cross-region paths allow hybrid builds. Keystone nodes are 8-45 point purchases accessible only through completing prerequisite chains.

9.5 Disadvantages as the Burden System

Implement a "Burden" system where players can opt-in to GURPS disadvantages at character creation and at specific Atlas nodes (the "Burden nodes"). Each Burden provides bonus Skill Points equal to its GURPS negative point value. Maximum Burden: −50 points (matching GURPS's campaign limit of −75, adjusted for game balance).

This is directly analogous to PoE's Ruthless mode or Hardcore choices but applied at the individual character trait level. A player who takes "The Mark of Davy Jones" (Cursed, −15) gets 15 bonus Skill Points but random catastrophic events throughout play. Pure mechanical opt-in risk/reward.

9.6 Damage Type Ecosystem

Implement all relevant GURPS wound types as distinct damage categories with their multipliers and special effects:

Damage Type	Multiplier	Special Effect
Cutting	×1.5	Bleed (3% HP/sec for 10 sec)
Impaling	×2	Vitals bonus (+×3 when targeting vitals)
Crushing	×1	+50% knockdown chance; best non-lethal
Piercing	×0.5 to ×2	Varies by size; no bleed
Burning	×1	Ignite (ongoing; armor-penetrating)
Corrosion	×1	Reduces target armor DR permanently this fight

Enemy armor types respond differently to each. A skeleton has Damage Resistance to cutting (bones don't bleed) but vulnerability to crushing (bones shatter). A ghost has immunity to physical but vulnerability to cold iron (special material type).

Implement the full GURPS Social Engineering reaction modifier system. Each faction has a visible Reaction Score (−6 to +6). All social interactions use 3d6 roll-under against the relevant social skill (Fast-Talk, Intimidation, Merchant, Leadership), modified by the faction's Reaction Score.

Social gameplay unlocks:

Quest content inaccessible to players without faction standing
Price differentials (−30% to +50% based on Reaction Score)
Crew recruitment quality and loyalty
Intelligence on enemy positions and loot locations
Safe harbor access or denial

A full social-build character with high IQ, Charisma, Voice, and Savoir-Faire (Pirate) should be able to play the game through influence rather than combat.

9.8 Critical Design Warning: Complexity Budget

GURPS is the most complex tabletop RPG system in widespread use. Its full implementation is unsuitable for real-time ARPG play without significant abstraction. The following GURPS elements should be:

Kept (core feel preserved):

3d6 roll-under resolution
Point-buy attribute/advantage system
Active defense (dodge/parry/block)
FP as action resource
Wound type differentiation
Reaction modifier social system

Simplified for ARPG flow:

Turn structure → real-time with stance-based approximation
Hit location → targeted attack modes (simplified from 16 to 6 zones)
Reload times → abstracted to attack speed stats (not literal turns)
Spell maintenance → duration timers
Encumbrance → tier system (Light/Medium/Heavy burden levels visible on UI)

Cut or postponed:

Detailed armor hit location coverage (too granular for real-time)
Weapon reach rules (abstracted into attack range categories)
Detailed NPC psychology (simplified to Reaction Score system)
All optional combat modifiers not mapped to a player-facing choice

The goal is GURPS-inspired, not GURPS-emulated. Every rule kept must earn its place through gameplay contribution, not fidelity to the tabletop source.

Appendix A: GURPS Probability Quick Reference

Skill  Success%  Fail%  Crit%  CritFail%
6      9.3%      90.7%  0.5%   16.2%
7      16.2%     83.8%  0.5%   9.3%
8      25.9%     74.1%  0.5%   4.6%
9      37.5%     62.5%  0.5%   2.8%
10     50.0%     50.0%  0.5%   1.4%
11     62.5%     37.5%  0.5%   0.5%
12     74.1%     25.9%  0.5%   0.5%
13     83.8%     16.2%  0.5%   0.5%
14     90.7%     9.3%   0.5%   0.5%
15     95.4%     4.6%   4.6%   0.5%
16     97.7%     2.3%   9.3%   0.5%
17     99.1%     0.9%   16.2%  0.5%
18     99.5%     0.5%   25.9%  0.5%
19     99.5%     0.5%   37.5%  0.5%
20     99.5%     0.5%   50.0%  0.5%

Note: Crit success = roll ≤ 4 OR ≤ (skill−10), whichever produces more crits. Crit fail = roll ≥ 18 OR ≥ (skill+10). At high skill, crit success range expands dramatically; at very low skill, crit fail range expands.

Appendix B: Key GURPS Source References

GURPS Basic Set: Characters (4th Ed, 2004) — Steve Jackson Games. Primary reference for attributes, advantages, disadvantages, skills, point costs.
GURPS Basic Set: Campaigns (4th Ed, 2004) — Combat rules, active defenses, hit locations, wound modifiers, equipment.
GURPS Martial Arts (4th Ed, 2008) — Techniques, fighting styles, Weapon Master, Trained by a Master, dual-wielding, grappling.
GURPS Low-Tech (4th Ed, 2010) — TL5 weapons, armor, ships, navigation, period-accurate gear statistics.
GURPS Magic (4th Ed, 2004) — Spell colleges, FP costs, spell prerequisites, magical colleges.
GURPS Thaumatology (4th Ed, 2010) — Threshold Magic, Ritual Path Magic, Syntactic Magic, custom magic system design.
GURPS Powers (4th Ed, 2005) — Power modifier framework, innate attacks, afflictions, cursed abilities.
GURPS Horror (4th Ed, 2002, updated) — Fright Checks, madness system, undead, curse mechanics.
GURPS Action 1: Heroes (4th Ed, 2012) — Wildcard skills, Impulse Buys, cinematic heroics.
GURPS Social Engineering (4th Ed, 2012) — Reaction rolls, influence mechanics, reputation, status.
GURPS Mass Combat (4th Ed, 2010) — Fleet combat, troop quality, commander rules.
GURPS Swashbucklers (3rd Ed, 1999) — Pirate setting reference; use with 4e conversion guidelines.
GURPS Ultra-Tech — Not relevant for TL5, but valuable for calibration contrast.

Document prepared for Salt & Steel design team. All GURPS rule references are from 4th Edition (2004+) except where noted. For 3rd Edition supplements (Swashbucklers), use the conversion guidelines in GURPS Basic Set: Characters pp. 10-11.