
Grinmar
Deterministic, zero-hallucination RPG ruleset for LLMs.
If you’ve ever tried to build a game or a structured interactive experience using standard LLMs, you already know the core problem: Generative models are sycophants.
They are hardwired to prioritize user satisfaction over mechanical integrity. They will fudge math, refuse to let a user fail, and endlessly hallucinate inventory items to keep the conversation moving. I wanted to build a lethal, rules-heavy dark fantasy RPG engine, and the default conversational drift made it impossible.
Instead of building a heavy API wrapper to manage the state externally, I engineered Grinmar—a prompt-based architecture that forces the model to act as a rigid, impartial state-machine.
Here is the exact logic I used to kill the sycophancy:
1. The 3-Tier Action Gate
LLMs drift when you let them generate narrative and calculate outcomes simultaneously. I forced a hard sequence break. Before the model is allowed to generate a single word of prose, it must output a bracketed [SYSTEM CALC] execution block at the top of the generation. It calculates the target threshold against the player's stats and locks in the outcome (Pass/Fail/Fatal) before the narrative tokens start streaming.
2. The S.I.I.N.S. Attrition Engine
Abstract hit points encourage LLMs to be forgiving. I stripped them out and built a strict 5-tier degradation track for Vitality and Stamina. The model cross-references standard attributes (Strength, Intuition, Intellect, Nimbleness, Social) against this track. If a player hits Tier-05 (Terminal Collapse), the logic gate forces immediate execution. Plot armor is disabled.
3. The Zero-Hallucination HUD
To stop context drift and inventory hallucination, the engine enforces a strict 5-slot persistent HUD at the end of every prompt. Consumed resources are immediately and permanently overwritten with an [Empty] marker. If it isn't in the ledger, the model is strictly forbidden from letting the player use it.
By forcing the math to lead the narrative, you can turn a conversational AI into a lethal Game Master.
I’ve compiled the core logic gates, the Monolith ruleset, and the survival dossier into a deployable package.
You can check out the live architecture deployment here:
https://graywolfone21.itch.io/grinmar
If anyone is working on taming LLM context drift or building similar procedural logic gates, I’d love to hear how you are handling state management.
About
LLMs make terrible game engines because they fudge math and hallucinate inventory. I built Grinmar to force models into a rigid, deterministic state-machine using pure mathematical prompt architecture.

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