How the AI Dungeon Master works

Nyxfall is a text role-playing game where an AI runs the world and a rules engine runs the mechanics. Those are two different jobs, and keeping them separate is the whole design.

The short version

You type what your character does, in plain English. The game works out what you meant, resolves it against fifth-edition-compatible rules in code — dice, modifiers, saving throws, spell slots — and then the AI narrates the outcome it was handed. The model describes what happened. It does not decide what happened.

What one turn actually does

1. You write an action. "I try to talk the guard into letting us through" or "I cast fireball at the two archers". There are no commands to memorise and no menus to hunt through, though the panels are there if you prefer clicking.

2. The game works out your intent. Your text is turned into a structured action — an attack, a spell, a skill check, a purchase, a conversation. Simple mechanical intents are recognised outright without asking a model at all.

3. The rules engine resolves it. This is ordinary code. It rolls the dice, applies your proficiency bonus and ability modifiers, checks whether you have the spell slot, applies cover and advantage, works out concentration, and applies conditions. The result is a fact before any prose exists.

4. The AI narrates the result. The Dungeon Master is given the outcome — "the attack hit for 8 slashing damage, the guard is now hostile" — and writes the scene. It streams a word at a time, so you read it as it is written.

5. The world updates. Damage, coin, inventory, quest state, the clock, the weather, how that guard feels about you from now on. All of it persists.

Why the split matters

An AI asked to both invent the story and adjudicate the rules will quietly do neither reliably. It will forget you are out of spell slots. It will let a hit land because a hit is more dramatic. It will award treasure it has no way to record, and the next session will not remember any of it.

Separating them fixes that. The dice are real dice and the numbers are real numbers, so a critical hit is a critical hit whether or not it makes a better sentence. The AI is left to do what it is genuinely good at: describing a place, voicing a character, and reacting to something you did that nobody planned for.

The world keeps going

Worlds are generated as layered hex maps — biomes, elevation, rivers, roads laid between real settlements — and the places you visit are filled in as you reach them. Towns are built from templates as clusters of buildings with streets, gates and working residents who keep schedules. Time passes on a campaign clock: travel takes days, food is eaten, and preserved rations spoil on a date.

The people remember you. Every character tracks its own relationship with each person it meets — how they feel about you, how deep the bond has grown, and what happened between you. A merchant you robbed does not greet you the same way next season.

Solo or with friends

Most people play alone; the Dungeon Master is a patient one and never needs scheduling. You can also share a campaign, and turns stream to everyone in real time.

What you need

A browser, and an AI provider key of your own — see what it costs. Characters are made with a guided walkthrough that will happily pick sensible options for you if you have never played a tabletop RPG before, and explain each one if you have.

Roll up a character