@quantaris/engine

Deterministic game logic for Quantaris — pure TypeScript, zero dependencies.

This is the canonical implementation of Quantaris game rules. The engine is 100% pure functions with no side effects, making it suitable for:

• Server-side turn resolution
• Client-side move preview
• Replay validation
• AI training and research
• Third-party tool development

Installation

npm install @quantaris/engine

Quick Start

import {
  createInitialState,
  resolveTurn,
  validatePlayerActions,
  hashState,

ActionType,
  Direction,
  Player,
} from "@quantaris/engine";

// Create a new game
const state = createInitialState();

// Define player actions (use enums, never hardcoded strings!)
const actionsA = [
  { type: ActionType.Move, quantarId: "A1", direction: Direction.North },
  { type: ActionType.Pulse, quantarId: "A2", direction: Direction.North },
  { type: ActionType.Shield, quantarId: "A3" },
];

const actionsB = [
  { type: ActionType.Shield, quantarId: "B1" },
  { type: ActionType.Shield, quantarId: "B2" },
  { type: ActionType.Move, quantarId: "B3", direction: Direction.South },
];

// Validate before resolution
const validationA = validatePlayerActions(state, actionsA, Player.A);
const validationB = validatePlayerActions(state, actionsB, Player.B);

if (validationA.valid && validationB.valid) {
  // Resolve the turn
  const result = resolveTurn({ state, actionsA, actionsB });
  
  console.log("New state:", result.state);
  console.log("Turn log:", result.log);
  console.log("State hash:", hashState(result.state));
}

Core Concepts

Entities

• Quantar: Active units controlled by players (3 per player, 2 HP each)
• Core: Passive objectives (1 per player, 5 HP, destroy to win)

Actions

Each Quantar can perform exactly one action per turn:

• MOVE: Move one cell orthogonally (N/E/S/W)
• PULSE: Fire a beam in a direction (hits first entity, 1 damage)
• SHIELD: Reduce incoming damage by 1 this turn

Turn Resolution

Turns are resolved in a deterministic order:

1. MOVE phase — All moves applied simultaneously
2. SHIELD phase — Shields activated
3. PULSE phase — Beams fired from post-move positions
4. DAMAGE phase — All damage applied simultaneously
5. CLEANUP — Remove destroyed entities, check win condition

API Reference

State Management

// Create initial game state
createInitialState(): GameState

// Query helpers
getQuantar(state, id): Quantar | undefined
getPlayerQuantars(state, playerId): Quantar[]
getPlayerCore(state, playerId): Core
getEntityAt(state, position): Entity | null

Validation

// Validate a single action
validateAction(state, action, playerId): ValidationResult

// Validate all actions for a turn
validatePlayerActions(state, actions, playerId): ValidationResult

Resolution

// Resolve a turn (pure function)
resolveTurn({ state, actionsA, actionsB }): TurnResult

Hashing

// Hash state for comparison/verification
hashState(state): string

// Check if two states are identical
statesEqual(a, b): boolean

// Canonical string representation
canonicalizeState(state): string

Types

type PlayerId = "A" | "B";
type Direction = "N" | "E" | "S" | "W";

interface Position {
  x: number; // 0-8
  y: number; // 0-8
}

interface Quantar {
  id: string;
  owner: PlayerId;
  position: Position;
  hp: number;
}

interface Core {
  owner: PlayerId;
  position: Position;
  hp: number;
}

interface GameState {
  turn: number;
  phase: GamePhase;        // GamePhase.Playing | GamePhase.Ended
  quantars: Quantar[];
  cores: { A: Core; B: Core };
  winner: PlayerId | null;
}

type Action = MoveAction | PulseAction | ShieldAction;

interface TurnResult {
  state: GameState;
  log: TurnLog;
}

Enums (No Hardcoded Strings!)

Always use these enums instead of string literals:

// Players
Player.A  // "A"
Player.B  // "B"

// Directions
Direction.North  // "N"
Direction.East   // "E"
Direction.South  // "S"
Direction.West   // "W"

// Action types
ActionType.Move    // "MOVE"
ActionType.Pulse   // "PULSE"
ActionType.Shield  // "SHIELD"

// Game phases (engine-level only)
GamePhase.Playing  // "playing"
GamePhase.Ended    // "ended"

Constants

BOARD_SIZE = 9          // 9x9 grid
CORE_HP = 5             // Core hit points
QUANTAR_HP = 2          // Quantar hit points
PULSE_DAMAGE = 1        // Damage per pulse hit
SHIELD_REDUCTION = 1    // Damage reduction from shield
QUANTARS_PER_PLAYER = 3 // Quantars per side

Design Principles

1. Pure Functions: No side effects, no mutations, no external state
2. Deterministic: Same inputs always produce same outputs
3. Zero Dependencies: Works anywhere TypeScript runs
4. Immutable Data: All state objects are readonly

License

MIT

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May the quants be with us. ⚛️