Tactical Dice Game System

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A foundational role-playing engine designed for humans, computers, and everything in between.

The Tactical Dice Game System (TDGS) is an open-source RPG engine released under the MIT license. It's not a complete game: it's the mechanical foundation for building them. TDGS provides mathematically transparent rules designed for computational verification, making it ideal for indie developers, AI-powered tools, and anyone who wants to build on tested mathematics rather than reinvent probability.

All contested actions resolve with one formula: d20 + (Your Stat − Their Stat) + Modifiers >= 11. The threshold is always 11; stat differences and modifiers do the rest. This scales cleanly from bar brawls to divine conflicts without table lookups or variable DCs. TDGS also introduces Luck as a permanent attribute rather than a spendable resource: positive Luck guarantees a minimum success rate, negative Luck caps your maximum. Fortune feels like destiny, not currency.

TDGS gives you the engine: resolution mechanics, nine attributes, unified progression, and combat rules with consistent lethality across all power tiers. It doesn't give you setting, monsters, or adventures. You build the game.

Built for Three Constituencies

TDGS is designed from the ground up to serve three audiences equally: humans at tables rolling physical dice, computers and software running deterministic simulations, and artificial intelligence that can learn, run, and assist with games. Every mechanic is transparent, every formula is explicit, and every document has an AI-optimized companion.

Documentation

Intent

The foundational design philosophy of TDGS. Why it exists, what it believes, and the immutable features that define the system. Start here.

Conventions and Concepts

How TDGS is organized and how to speak its language. Project architecture, terminology standards, contribution guidelines, and the three constituencies TDGS serves.

Document 1: Dice and Uncertainty

How uncertainty is resolved in TDGS. Dice taxonomy, resolution vs magnitude, critical outcomes, and when to roll.

Document 2: Core Attributes (Stats)

The nine foundational attributes: STR, DEX, REF, CON, MOV, INT, WIS, CHA, and LUK. What they measure and what they don't.

Document 3: Resolution Mechanics

The core formula for resolving uncertain actions. One formula, one threshold, infinite possibilities. Natural extremes, stat pairings, and critical outcomes.

Document 4: Luck

The attribute that bends reality. Intentionally unfair, deliberately powerful, carefully constrained. How luck sets floors and ceilings on probability.

Document 5: Action Taxonomy

What you can do, and what it costs. Physical, Mental, Magical, Utility, and Defensive actions with optional Technology and Psionics expansions.

Document 6: Action Economy

When you act, how often, and in what order. Scenes, Rounds, Initiative, Instants, and Interrupts.

Document 7: Abilities

What you can do beyond your innate capabilities. Skills, Spells, and Traits: the three types of abilities and how they work.

Document 8: Combat

How damage is dealt, absorbed, and survived. Hit Points, damage calculation, armor systems, healing, and conditions.

Document 9: Entities

What things ARE in the game world. The universal structure for player characters, NPCs, creatures, and anything that can act.

Document 10: Classes

What you've become through training. How classes grant abilities, unlock tiers, and provide stat bonuses. Template classes included.

Document 11: Races

What you ARE, inherently. Stat ranges, natural weapons and armor, innate traits. Template races from Goblin to Dragon.

Document 12: Progression

How you grow and advance. XP system, the Difficulty Spectrum, leveling costs, stat increases, and the Legend Wall.

Document 13: Character Creation

Building a character from scratch. The seven-step process for creating TDGS characters: Race, Stats, Luck, Class, Bonuses, Derived Values, and Finishing Touches.

Document 14: Movement & Positioning

Spatial mechanics for tactical play. Distance systems (grid and range bands), movement actions, terrain types, cover, opportunity attacks, flanking, and forced movement.

Document 15: Equipment & Slots

What you wear, wield, and carry. Slot types, equipped vs carried, item structure, carrying capacity, and slot management.

Document 16: Area of Effect

How AoE works in TDGS. Distance measurement (Chebyshev), standard shapes (circle, cone, line, rectangle), notation, height, origin, and resolution.

Document 17: Damage

Damage Types as a framework. Resistance (75% cap), Vulnerability (no cap), Immunity (the sole exception to minimum damage), Absorption, and the Damage Pipeline.

Mounts & Vehicles

Rules for mounts (creatures you ride) and vehicles (conveyances you operate). Covers creation, progression, action economy, combat, and traits.

Crafting

Rules for creating items. Skill-based quality pools, batch crafting, recipes, and the relationship between crafting and XP.

Mass Combat

Rules for armies and warfare. Units as entities, commanders, orders, morale cascades, routing, and rally mechanics.

Glossary

Canonical definitions for all TDGS terminology. When a term appears in any document, its authoritative meaning is defined here with links to source documents.

Open Source: TDGS engine specifications are released under the MIT License. Use them, modify them, build on them, just say it's TDGS-based.