RPG-MCP: Agentic Embodied Simulation Kernel

A deterministic, schema-driven, multi-world simulation engine for embodied AI agents.

RPG-MCP is not a gameit's a world kernel. It provides the physics, constraints, persistence, and deterministic execution layer that allows LLM agents to inhabit a simulated reality with real bodies, real limits, and real consequences.

What's New (December 2025)

Latest Release

• 145+ MCP Tools - Complete RPG mechanics coverage with new composite tools
• 800+ Passing Tests - Comprehensive test coverage across all systems
• Composite Tools (TIER 1) - Reduce token overhead by 80-95% for common workflows
• Preset Systems - 1100+ creature presets, 50+ encounter presets, 30+ location presets
• Schema Shorthand (TIER 2) - Token-efficient position/stats parsing
• Batch Repository Methods - Optimized for world generation workflows
• Location Presets - Tavern, dungeon, temple, market presets with full population
• Encounter Presets - Level-scaled encounters (goblin ambush, undead crypt, dragon's lair)

Core Systems

• Full Spellcasting System - 15+ SRD spells, class progression, slot tracking
• Theft & Fence System - Heat decay, witness tracking, black market economy
• Corpse & Loot System - Decay states, harvestable resources, loot tables
• NPC Memory System - Relationship tracking, conversation history, context injection
• Improvisation Engine - Rule of Cool stunts, custom effects, arcane synthesis
• Legendary Creatures - Lair actions, legendary resistances, boss mechanics
• Death Saving Throws - Full D&D 5e rules with stabilization
• Spatial Navigation - Room networks, terrain-aware POI placement
• Narrative Memory Layer - Session notes, plot threads, NPC voices, foreshadowing
• Currency System - Gold/silver/copper with auto-conversion

Architecture Philosophy

This engine implements the Event-Driven Agentic AI Architecture:

                                                                                         
   EVENT                                                                                 
                                                                                        
                                                                                        
                        
     OBSERVE      ORIENT        DECIDE         ACT      VALIDATE  
                                                                              
    MCP Read        LLM Brain      Orchestrator      MCP Write       Engine   
     Tools           Analyze          Plan             Tools          Rules   
                        
                                                                                      
                                                                                      
               
                                    WORLD STATE                                         
                                  (updates & loops)                                     
                                                                                         

The Embodiment Model

Key invariant: LLMs propose intentions. The engine validates and executes. LLMs never directly mutate world state.

Features

Core Systems

Multi-tenant & Multi-world

• Isolated projects (projectId) and parallel worlds (worldId)
• Fork worlds for branching timelines or "what-if" simulations

Embodied Entities

• Position, velocity, orientation in 3D space
• Stats, inventories, status effects, controller links
• Sensory radius, line-of-sight, perception limits

Intent-Based Actions

• Agents submit intentions: MOVE_TO, ATTACK, CAST_SPELL, INTERACT
• Engine validates against physics, rules, and constraints
• Invalid actions rejected with structured feedback

Deterministic Physics

• Collision detection, projectile trajectories, movement costs
• Reproducible world stepssame inputs always yield same outputs
• Full audit trail: snapshots, event logs, action history

Combat & Encounters

• Initiative tracking with advantage/disadvantage
• Spatial combat with grid positioning and collision
• Opportunity attacks with reaction economy
• Death saving throws (D&D 5e rules)
• Damage resistance/vulnerability/immunity
• Legendary creatures with lair actions and legendary resistances
• Encounter presets - Pre-balanced encounters by party level

Magic System

• 15+ SRD spells (Magic Missile, Fireball, Cure Wounds, etc.)
• Spell slot tracking with class-based progression
• Warlock pact magic with short rest recovery
• Concentration tracking
• Anti-hallucination validation - LLMs cannot cast spells they don't know
• Rest mechanics restore spell slots and HP

Theft & Economy

• Stolen item tracking with heat levels (burning cold)
• Witness recording for …