Grinmar: The Deterministic RPG Engine

GRINMAR: A Ruthless Solo-TTRPG Engine

No safety nets. No plot armor. An impartial Game Master that never fudges the dice.

Grinmar is a grimdark solo tabletop roleplaying ruleset designed to transform AI into a brutally unforgiving, mathematically strict Game Master. You step into a world carved into six shattered continents where humanity claws for survival amidst entropic rot, flesh-woven anomalies, and cosmic dread.  

This is not a traditional text adventure that agrees with your every move. The Arbiter will not rescue you, will not spawn convenient loot, and will never soften the consequences of a fatal mistake. If you lack the physical stats or the tactical foresight, you fail.  

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📦 WHAT'S IN THE BOX

1. Grinmar Core Edition (The Full Campaign Ruleset)

The definitive solo tabletop engine. Balanced for deep roleplay, rich sensory exploration, and dynamic NPC psychology. It features hidden faction motivations, deep urban safe-zone downtime, and a procedural eldritch crafting system.  

2. Grinmar Monolith Edition (Hardcore / Iron-Man Mode)

A stripped-down, uncompromising system architecture built strictly for high-focus tacticians. The Game Master is locked into a rigid syntax, forced to output a hard mathematical check at the top of every single turn. It enforces strict word limits to eliminate fluff, and utilizes diegetic reality fractures (e.g., rusted iron singing wrong) to force you to verify your ledger and maintain true inventory accuracy.  

3. Grinmar: World Lore & Faction Dossier

A beautifully formatted, immersive gazetteer detailing the six continents, the physical laws of survival, and the psychologies of the major ideological factions (such as the fanatic Iron-Priests of the Anchorite Creed and the twisted zealots of the Cult of the Molt).  

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⚙️ HOW TO PLAY (Bring-Your-Own-GM)

Download your preferred Edition and read the World Dossier.

Open your AI interface of choice (ChatGPT, Claude, Grok, or a local offline model).

Paste the ruleset text into a fresh chat to initialize the Arbiter.

Type your character's opening action to trigger Phase 0 (The Genesis Algorithm).  

Describe your character’s background and flaws in plain English so the GM can permanently lock in your starting stats—then try to survive.  

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🗡️ MECHANICS THAT BITE

The S.I.I.N.S. Matrix: Every physical threshold and survival check is bound to your Strength, Intuition, Intellect, Nimbleness, and Social leverage.  

Deterministic 3-Tier Action Gate: The Game Master evaluates every action through strict inventory verification, environmental difficulty thresholds (DT 10–50), and kinetic fallout.  

The Attrition Engine: Damage is never abstract. You will suffer physical degradation across four-tiered Vitality and Stamina tracks that cripple your active stats in real-time.  

Procedural Affix Loot: Scavenge mundane scrap or risk life and limb attempting to graft eldritch anomalies onto your weapons. One failed intellectual check detonates the catalyst and permanently scars your character.  

Zero-Invention Rule & Hard Pack Limits: You possess a strict 5-slot inventory. The GM is explicitly forbidden from generating miraculous exits or unearned loot. When an item is spent through crafting or triage, it is permanently purged.  

Prepare your bloodline. The Arbiter does not forgive.