Game Architecture Patterns

Reference knowledge for building well-structured browser games. These patterns apply to both Three.js (3D) and Phaser (2D) games.

Reference Files

For detailed reference, see companion files in this directory:

system-patterns.md — Object pooling, delta-time normalization, resource disposal, wave/spawn systems, buff/powerup system, haptic feedback, asset management

Core Principles

Core Loop First: Implement the minimum gameplay loop before any polish. The order is: input -> movement -> fail condition -> scoring -> restart. Only after the core loop works should you add visuals, audio, or juice. Keep initial scope small: 1 scene/level, 1 mechanic, 1 fail condition.
Event-Driven Communication: Modules never import each other for communication. All cross-module messaging goes through a singleton EventBus with predefined event constants.
Centralized State: A single GameState singleton holds all game state. Systems read state directly and modify it through events. No scattered state across modules.
Configuration Centralization: Every magic number, balance value, asset path, spawn point, and timing value goes in Constants.js. Game logic files contain zero hardcoded values.
Orchestrator Pattern: One Game.js class initializes all systems, manages game flow (boot -> gameplay -> death/win -> restart), and runs the main loop. Systems don't self-initialize. No title screen by default — boot directly into gameplay. Only add a title/menu scene if the user explicitly asks for one.
Restart-Safe and Deterministic: Gameplay must survive full restart cycles cleanly. GameState.reset() restores a complete clean slate. All event listeners are removed in cleanup/shutdown. No stale references, lingering timers, leaked tweens, or orphaned physics bodies survive across restarts. Test by restarting 3x in a row — the third run must behave identically to the first.
Clear Separation of Concerns: Code is organized into functional layers:
- core/ - Foundation (Game, EventBus, GameState, Constants)
- systems/ - Engine-level systems (input, physics, audio, particles)
- gameplay/ - Game mechanics (player, enemies, weapons, scoring)
- level/ - World building (level construction, asset loading)
- ui/ - Interface (menus, HUD, overlays)

Event System Design

Event Naming Convention

Use domain:action format grouped by feature area:

export const Events = {
  // Player
  PLAYER_DAMAGED: 'player:damaged',
  PLAYER_HEALED: 'player:healed',
  PLAYER_DIED: 'player:died',

  // Enemy
  ENEMY_SPAWNED: 'enemy:spawned',
  ENEMY_KILLED: 'enemy:killed',

  // Game flow
  GAME_STARTED: 'game:started',
  GAME_PAUSED: 'game:paused',
  GAME_OVER: 'game:over',

  // System
  ASSETS_LOADED: 'assets:loaded',
  LOADING_PROGRESS: 'loading:progress'
};

Event Data Contracts

Always pass structured data objects, never primitives:

// Good
eventBus.emit(Events.PLAYER_DAMAGED, { amount: 10, source: 'enemy', damageType: 'melee' });

// Bad
eventBus.emit(Events.PLAYER_DAMAGED, 10);

State Management

GameState Structure

Organize state into clear domains:

class GameState {
  constructor() {
    this.player = { health, maxHealth, speed, inventory, buffs };
    this.combat = { killCount, waveNumber, score };
    this.game = { started, paused, isPlaying };
  }
}

Game Flow

Standard flow for both 2D and 3D games:

Boot/Load -> Gameplay <-> Pause Menu (if requested)
                      -> Game Over -> Gameplay (restart)

No title screen by default. Games boot directly into gameplay. The Play.fun widget handles score display, leaderboards, and wallet connect in a deadzone at the top of the game, so no in-game score HUD is needed. Only add a title/menu scene if the user explicitly requests one.

Common Architecture Pitfalls

Unwired physics bodies — Creating a static physics body (e.g., ground, wall) without wiring it to other bodies via physics.add.collider() or physics.add.overlap() has no gameplay effect. Every boundary or obstacle needs explicit collision wiring to the entities it should interact with. After creating any static body, immediately add the collider call.
Interactive elements blocked by overlapping display objects — When building UI (buttons, menus), the topmost display object in the scene list receives pointer events. Never hide the interactive element behind a decorative layer. Either make the visual element itself interactive, or ensure nothing is rendered on top of the hit area.
Polish before gameplay — Adding particles, screen shake, and transitions before the core loop works is a common time sink. Get input -> action -> fail condition -> scoring -> restart working first. Everything else is polish.
No cleanup on restart — Forgetting to remove event listeners, destroy timers, and dispose resources in shutdown() causes ghost behavior, double-firing events, and memory leaks after restart.

Pre-Ship Validation Checklist

Before considering a game complete, verify all items:

game-architecture