Steelkilt - Draft RPG Combat System

A Rust implementation of the Draft 0.4 RPG rule set.

Based on the "Draft 0.4 RPG Rule Set" by Pitt Murmann (1993-1998), this library provides a reusable combat system for tabletop role-playing games.

Features

Core Systems Implemented

• 9 Attributes System: Physical (STR, DEX, CON), Mental (REA, INT, WIL), and Interactive (CHA, PER, EMP)
• Skill-Based Combat: Attack, parry, and dodge mechanics using d10 rolls
• Weapon System: Impact-based damage with various weapon types (daggers, swords, etc.)
• Armor System: Protection values with movement penalties
• Wound Tracking: Light, Severe, and Critical wounds with stacking mechanics
• Combat Rounds: Turn-based combat resolution

Combat Mechanics

The combat system follows the Draft RPG rules:

1. Attack Roll = Weapon Skill + d10 + Modifiers
2. Defense Roll = Weapon Skill (parry) or Dodge Skill + d10 + Modifiers
3. Damage = Attack Roll - Defense Roll + Strength Bonus + Weapon Damage - Armor Protection

Wound Levels (based on damage vs Constitution):

• Light: damage ≤ CON/2 (penalty: -1 per wound)
• Severe: damage ≤ CON (penalty: -2 per wound)
• Critical: damage ≤ 2×CON (penalty: -4 per wound)
• Death: damage > 2×CON or 2+ Critical wounds

Wound Stacking:

• 4 Light wounds → 1 Severe wound
• 3 Severe wounds → 1 Critical wound
• 2 Critical wounds → Death

Installation

Add steelkilt to your Cargo.toml:

[dependencies]
steelkilt = "0.1.0"

# With serde support for JSON serialization
steelkilt = { version = "0.1.0", features = ["serde"] }

Or build from source:

cargo build --release

Usage

As a Library

use steelkilt::*;

// Create attributes (STR, DEX, CON, REA, INT, WIL, CHA, PER, EMP)
let attrs = Attributes::new(8, 6, 7, 5, 6, 5, 5, 7, 4);

// Create a character
let mut fighter = Character::new(
    "Aldric",
    attrs,
    7,  // weapon skill
    5,  // dodge skill
    Weapon::long_sword(),
    Armor::chain_mail(),
);

// Create an opponent
let mut opponent = Character::new(
    "Grimwald",
    Attributes::new(9, 5, 8, 4, 5, 6, 4, 6, 3),
    6,  // weapon skill
    4,  // dodge skill
    Weapon::two_handed_sword(),
    Armor::leather(),
);

// Execute combat round
let result = combat_round(&mut fighter, &mut opponent, DefenseAction::Parry);

if result.hit {
    println!("{} hit {} for {} damage!", result.attacker, result.defender, result.damage);
}

Interactive Combat Simulation

Run the interactive combat simulator:

cargo run --bin combat-sim

The simulation features:

• Pre-generated characters with different attributes and equipment
• Turn-based combat with player input for defense actions
• Real-time wound tracking and status updates
• Detailed character sheets and combat logs

Project Structure

steelkilt/
├── src/
│   ├── lib.rs              # Core library implementation
│   ├── modules/            # Advanced feature modules
│   │   ├── mod.rs          # Module exports
│   │   ├── skills.rs       # Skill development system
│   │   ├── exhaustion.rs   # Exhaustion tracking
│   │   ├── maneuvers.rs    # Combat maneuvers
│   │   ├── hit_location.rs # Hit location tracking
│   │   ├── ranged_combat.rs # Ranged combat mechanics
│   │   └── magic.rs        # Magic system
│   └── bin/
│       └── combat_sim.rs   # Interactive combat simulation
├── examples/
│   ├── quick_combat.rs     # Basic combat example
│   ├── advanced_features.rs # Showcase of all advanced features
│   └── magic_combat.rs     # Wizard duel simulation
├── Cargo.toml
└── README.md

Core Types

Attributes

Contains all 9 character attributes (range 1-10)

Character

Represents a combatant with attributes, skills, equipment, and wounds

Weapon

Weapon definitions with impact levels (Small=1, Medium=2, Large=3, Huge=4)

Armor

Armor types with protection values and movement penalties

Wounds

Tracks Light, Severe, and Critical wounds with automatic stacking

CombatResult

Contains the outcome of a combat round

Testing

Run the test suite:

cargo test

The project includes 39 comprehensive tests covering:

Core Combat System:

• Dice rolling (d10 range validation)
• Attribute calculations
• Wound stacking mechanics
• Death thresholds

Advanced Features:

• Skill progression and cost calculation (6 tests)
• Exhaustion levels and recovery (4 tests)
• Combat maneuvers and modifiers (6 tests)
• Hit location determination and damage (6 tests)
• Ranged combat mechanics and modifiers (7 tests)
• Magic system, spell casting, and exhaustion (7 tests)

All tests validate proper implementation of Draft 0.4 RPG rules.

Draft RPG Rules Reference

This implementation is based on specific rules from Draft 0.4:

Core Systems:

• Section 2.4-2.9: Attributes system (9 attributes)
• Section 3: Skills and skill checks
• Section 3.13: Skill development and progression
• Section 4.17-4.24: Combat mechanics
  • Attack/parry/dodge rolls
  • Weapon impact and armor protection
  • Damage calculation
  • Wound levels and stacking
  • Death conditions

Advanced Features:

• Section 4.21: Ranged combat mechanics
• Section 4.22: Special combat maneuvers
• Section 4.24.1: Exhaustion system
• Section 4.24.3: Hit location tracking
• Chapter 5: Magic system (9 branches of magic)

License

This implementation is released under the MIT license. The original Draft 0.4 RPG Rule Set was released under the OpenContent License (OPL) Version 1.0.

Example Combat Output

=== DRAFT RPG COMBAT SIMULATOR ===

╔═══════════════════════════════════════╗
║ Aldric the Bold                       ║
╠═══════════════════════════════════════╣
║ PHYSICAL ATTRIBUTES:                  ║
║   STR: 8   DEX: 6   CON: 7            ║
║ Weapon: Long Sword                    ║
║   Damage: 5                           ║
║ Armor: Chain Mail                     ║
║   Protection: 3                       ║
╚═══════════════════════════════════════╝

--- ROUND 1 ---

Aldric the Bold's turn to attack!
How does Grimwald Ironfist defend? [P]arry or [D]odge? p

>>> Attack: Aldric the Bold rolls 14 vs Grimwald Ironfist's defense 11
>>> HIT! 6 damage dealt
>>> Severe wound inflicted!

Advanced Features

The library now includes comprehensive implementations of advanced Draft RPG mechanics:

1. Skill Development & Progression (Section 3.13)

Complete skill learning and advancement system with:

• Skill Difficulty Classes: Easy, Normal, Hard, Very Hard
• Progressive Cost System: Costs increase beyond attribute scores
• Prerequisites: Skills can require other skills at minimum levels
• Skill Points: Track and manage character advancement

use steelkilt::modules::*;

let mut skill_set = SkillSet::new(30); // 30 skill points

// Add skills with different difficulties
let sword = Skill::new("Longsword", 7, SkillDifficulty::Normal);
skill_set.add_skill(sword);

// Raise skill level
skill_set.raise_skill("Longsword").unwrap();

Cost Mechanics:

• Normal skills: 1 point per level up to attribute score
• Easy skills: 1 point total to reach attribute score
• Hard skills: 2x normal cost
• Very Hard skills: 3x normal cost
• Beyond attribute score: costs increase progressively

2. Exhaustion System (Section 4.24.1)

Track physical and magical exhaustion:

• Exhaustion Levels: None, Light, Severe, Critical
• Combat Fatigue: 1 point per combat round
• Penalties: -1 to -4 based on exhaustion level
• Recovery: 1 point per 2 rounds of rest
• Willpower Checks: Required at Severe+ levels

let mut exhaustion = Exhaustion::new(stamina);
exhaustion.add_points(1); // Each combat round
let penalty = exhaustion.penalty(); // -1 to -4
exhaustion.rest(10); // Recover from rest

3. Special Combat Maneuvers (Section 4.22)

Tactical combat options:

• Normal: Standard attack (+0/+0/+0)
• Defensive Position: +2 defense, cannot attack
• Charge: +1 attack, +1 damage, -2 defense
• All-Out Attack: +2 attack, -4 defense (risky!)
• Aimed Attack: -2 attack, +2 damage (requires aiming)

use steelkilt::modules::*;

let mut stance = CombatStance::new();
stance.set_maneuver(CombatManeuver::Charge).unwrap();

// Apply modifiers
let attack_bonus = stance.total_attack_modifier(); // +1
let defense_penalty = stance.total_defense_modifier(); // -2
let damage_bonus = stance.total_damage_modifier(); // +1

4. Hit Location Tracking (Section 4.24.3)

Detailed wound tracking by body part:

• 6 Hit Locations: Head, Torso, Left/Right Arm, Left/Right Leg
• Attack Direction: Front/Back/Left/Right/Above/Below
• Damage Multipliers: Head 1.5x, Torso 1.0x, Limbs 0.75x
• Disabling Wounds: Severe hits can disable limbs
• Severed Limbs: Multiple Critical wounds can sever

use steelkilt::modules::*;

let location = HitLocation::determine(AttackDirection::Front);
let multiplier = location.damage_multiplier();

let mut arm = LocationalDamage::new(HitLocation::RightArm);
arm.add_wound(WoundSeverity::Severe);
if !arm.is_functional() {
    println!("Arm disabled!");
}

5. Ranged Combat (Section 4.21)

Complete ranged weapon system:

• Weapon Types: Bows, crossbows, firearms, thrown weapons
• Range Modifiers: Point blank, medium, max range
• Aiming System: +1 bonus after 1 round of aiming
• Target Size: -4 (Tiny) to +6 (Gigantic)
• Cover: None, Partial (-2), 3/4 (-4), Full (-8)
• Preparation Time: Different for each weapon type

use steelkilt::modules::*;

let bow = RangedWeapon::long_bow();
let mut state = RangedAttackState::new();

state.prepare_weapon(&bow);
state.start_aiming();
state.continue_aiming(); // Aim for a round

let modifier = calculate_ranged_modifiers(
    50,                    // distance in meters
    TargetSize::Medium,
    Cover::Partial,
    &bow,
    &state,
);

state.fire().unwrap(); // Shoot!

Weapon Examples:

• Short Bow: 20m point blank, 100m max, damage 4
• Long Bow: 30m point blank, 120m max, damage 6
• Crossbow: 30m point blank, 100m max, damage 6 (slow reload)
• Rifle: 40m point blank, 200m max, damage 8

6. Magic System (Chapter 5)

Full implementation of Draft RPG magic:

• 9 Branches of Magic: Alchemy, Animation, Conjuration, Divination, Elementalism, Mentalism, Necromancy, Thaumaturgy, Transportation
• Lore System: Must learn branch lore before spells
• Spell Difficulty: Easy (8), Normal (10), Hard (12) target numbers
• Magical Exhaustion: Casting causes exhaustion based on spell power
• Empathy Attribute: Core attribute for magic use

use steelkilt::modules::*;

let mut mage = MagicUser::new(7); // Empathy 7

// Learn a branch of magic
mage.add_lore(MagicBranch::Divination, 5);

// Create and learn a spell
let spell = Spell {
    name: "Detect Magic".to_string(),
    branch: MagicBranch::Divination,
    difficulty: SpellDifficulty::Easy,
    preparation_time: 5,
    casting_time: 1,
    range: SpellRange::Short(20),
    duration: SpellDuration::Minutes(10),
};

mage.learn_spell(spell, 4).unwrap(); // Level 4 skill

// Cast spell: skill + empathy + roll
let result = mage.cast_spell("Detect Magic", d10()).unwrap();
if result.success {
    println!("Quality: {}", result.quality);
}

// Magical exhaustion penalties apply
let penalty = mage.exhaustion_penalty();

Branches of Magic:

• Divination (Normal): Gather information, foresee events
• Alchemy (Hard): Transform matter
• Elementalism (Very Hard): Control fire, water, air, earth
• Conjuration (Very Hard): Summon creatures
• Necromancy (Very Hard): Control undead
• Thaumaturgy (Hard): Telekinesis, control matter
• Transportation (Very Hard): Teleportation, time travel
• Animation (Hard): Healing, physical enhancement
• Mentalism (Hard): Mind reading, mental control

Examples

The project includes comprehensive examples:

Quick Combat

cargo run --example quick_combat

Basic melee combat demonstration showing the core combat system in action.

Advanced Features Demo

cargo run --example advanced_features

Comprehensive showcase of all advanced features:

• Skill progression with different difficulties
• Combat maneuvers (charge, defensive position, etc.)
• Exhaustion tracking during extended combat
• Hit location determination and effects
• Ranged combat with modifiers
• Magic system with spell casting

Magic Combat (Wizard's Duel)

cargo run --example magic_combat

Simulated duel between two magic users demonstrating:

• Offensive and defensive spell casting
• Magical exhaustion tracking
• Spell quality and targeting
• Multiple magic branches (Elementalism, Necromancy, Animation, Mentalism)
• Integration of magic with the wound system