Classic Game Engine

The Classic Game Engine powers text-based adventure games in Super Text Adventure. You define your entire game world as a JSON document, and the engine handles parsing player commands, managing state, and running all game mechanics.

What You Can Build

Explorable Worlds

Rooms connected by exits with descriptions, hidden passages, locked doors, and directional navigation.

Items & Inventory

Pickupable items, containers with locks, weapons, healing potions, and items that interact with the world.

NPCs & Quests

Characters with branching dialogue trees, item trading, quest flags, gated conversations, and patrol movement.

Combat & Dice

Turn-based combat with initiative, attack/defend/flee, weapons, armor, D&D-style dice rolls, and hostile creatures that ambush the player.

How It Works

1. You write a JSON file describing your world - rooms, items, NPCs, and creatures.

2. The engine loads your JSON as the world_data.

3. Players type natural-language commands like go north, take sword, or talk to wizard.

4. The CommandParser translates input into structured commands (verb + target + modifier).

5. The Engine routes commands to the appropriate Handler (movement, items, combat, etc.).

6. The handler processes the command, updates game state, and returns a text response.

Top-Level JSON Structure

Every game world is defined by a single JSON object with these top-level keys:

// world_data.json
{
  "meta": {
    "name": "My Adventure",
    "description": "A short quest to retrieve the Crystal of Power.",
    "starting_room": "tavern",
    "version": "1.0"
  },
  "rooms":     { /* room definitions */ },
  "items":     { /* item definitions */ },
  "npcs":      { /* NPC definitions */ },
  "creatures": { /* creature definitions */ }
}

Validation Contract

The engine checks every world against a machine-readable contract before a game starts, and the same files are published here so other tools can validate worlds exactly the same way:

> world.schema.json - JSON Schema for the document shape, with engine defaults recorded on the fields

> world.refs.json - every place an id is referenced and which collection it must exist in

> index.json - a corpus of valid, invalid, and lint worlds; each invalid one lists the error codes a validator must produce, and each lint one lists the advisory warnings a linter should report

Error codes are stable: schema.invalid, starting_room.missing, ref.missing, topic.missing, dice.outcomes, dice.consume_on, and attack_condition.invalid. Unknown keys are allowed everywhere except attack_condition, and meta.editor is reserved for editor tooling and never validated.

Quick Links

> World Builder - build and validate a world in your browser, no account needed; works offline

> World Structure - Full top-level schema details

> Rooms - Defining rooms, descriptions, and entry events

> Exits - Simple and complex exits, locks, hidden passages

> Items - All item types: weapons, consumables, keys, and more

> NPCs & Dialogue - Characters, dialogue trees, and quests

> Creatures - Enemies and their combat stats

> Combat - Turn-based combat mechanics

> Dice Rolls - D&D-style skill checks

> Flags & State - Global flags and game state tracking

> Containers - Openable and lockable containers

> Commands - All player commands and synonyms

> Full Example - A complete game world JSON