feat: Implement sound system and toggle functionality

- Introduced SoundSystem to manage sound events using the Web Audio API.
- Added SoundEvent component to represent different sound types (e.g., coin, damage, powerup).
- Integrated sound event emissions in the Game class for various actions (e.g., collecting coins, taking damage).
- Updated UI to include a sound status indicator with toggle functionality using the 'M' key.
- Enhanced game experience with background music and sound effects for actions, improving player engagement.

This update enriches the gameplay by adding audio feedback, enhancing the overall user experience.

index.html

@@ -96,6 +96,20 @@
             z-index: 100;
             font-family: 'Courier New', monospace;
         }
+        #soundStatus {
+            position: absolute;
+            top: 20px;
+            right: 100px;
+            font-size: 20px;
+            cursor: pointer;
+            z-index: 100;
+            user-select: none;
+            opacity: 0.8;
+            transition: opacity 0.2s;
+        }
+        #soundStatus:hover {
+            opacity: 1;
+        }
         #perfMonitor {
             position: absolute;
             top: 60px;
@@ -125,6 +139,11 @@
                 top: 10px;
                 right: 10px;
             }
+            #soundStatus {
+                top: 10px;
+                right: 60px;
+                font-size: 18px;
+            }
             #perfMonitor {
                 top: 40px;
                 right: 10px;
@@ -144,6 +163,8 @@
     
     <div id="version">v<span id="versionNumber">-</span></div>
     
+    <div id="soundStatus" title="Sound ON (Press M to mute)">🔊</div>
+    
     <div id="perfMonitor">
         <div><span class="label">FPS:</span> <span id="fps">60</span></div>
         <div><span class="label">Frame:</span> <span id="frameTime">16.7</span>ms</div>
@@ -159,7 +180,7 @@
     
     <div id="instructions">
         <p><strong>Controls:</strong> WASD or Arrow Keys to move | Touch and drag to move (mobile) | Collect yellow coins | Avoid red obstacles!</p>
-        <p style="margin-top: 5px; font-size: 11px; opacity: 0.7;">Press "T" or shake device to toggle performance monitor</p>
+        <p style="margin-top: 5px; font-size: 11px; opacity: 0.7;">Press "T" to toggle performance monitor | Press "M" to toggle sound</p>
     </div>
 
     <script type="module">

src/components/SoundEvent.js

@@ -0,0 +1,21 @@
+/**
+ * SoundEvent component - represents a sound that should be played
+ * Entities can add this component to trigger sounds, which SoundSystem will process
+ */
+export class SoundEvent {
+  /**
+   * @param {string} type - Sound type: 'coin', 'damage', 'powerup', 'combo', 'health', 'gameover', 'highscore'
+   * @param {number} [value] - Optional value (e.g., combo multiplier)
+   */
+  constructor(type, value = null) {
+    /** @type {string} Sound event type */
+    this.type = type;
+    
+    /** @type {number|null} Optional value for the sound (e.g., combo multiplier) */
+    this.value = value;
+    
+    /** @type {boolean} Whether this event has been processed */
+    this.processed = false;
+  }
+}
+

src/game/Game.js

@@ -13,6 +13,7 @@ import { CollisionSystem } from '../systems/CollisionSystem.js';
 import { InvincibilitySystem } from '../systems/InvincibilitySystem.js';
 import { ParticleSystem } from '../systems/ParticleSystem.js';
 import { PowerUpSystem } from '../systems/PowerUpSystem.js';
+import { SoundSystem } from '../systems/SoundSystem.js';
 import { RenderSystem } from '../systems/RenderSystem.js';
 
 // Components
@@ -21,6 +22,7 @@ import { Health } from '../components/Health.js';
 import { Invincibility } from '../components/Invincibility.js';
 import { CoinType } from '../components/CoinType.js';
 import { PowerUp } from '../components/PowerUp.js';
+import { SoundEvent } from '../components/SoundEvent.js';
 
 /**
  * Main Game class - manages the game loop and coordinates all systems.
@@ -248,6 +250,10 @@ export class Game {
     });
     this.world.addSystem(this.collisionSystem);
 
+    // Sound system (processes SoundEvent components)
+    this.soundSystem = new SoundSystem();
+    this.world.addSystem(this.soundSystem);
+
     // Rendering (must be last to sync transforms)
     this.world.addSystem(new RenderSystem(this.scene));
   }
@@ -306,6 +312,14 @@ export class Game {
     const coinType = this.world.getComponent(coinEntity, CoinType);
     const coinPosition = coinTransform ? coinTransform.position.clone() : null;
 
+    // Emit sound event BEFORE destroying the entity
+    const soundEntity = this.world.createEntity();
+    if (coinType && coinType.type === 'health') {
+      this.world.addComponent(soundEntity, new SoundEvent('health'));
+    } else {
+      this.world.addComponent(soundEntity, new SoundEvent('coin'));
+    }
+
     // Remove coin
     this.entityFactory.destroyEntity(coinEntity);
     const index = this.coins.indexOf(coinEntity);
@@ -354,11 +368,19 @@ export class Game {
 
     if (timeSinceLastCoin <= GameConfig.COMBO_TIME_WINDOW && this.lastCoinTime > 0) {
       // Maintain combo
+      const oldMultiplier = this.comboMultiplier;
       this.comboMultiplier = Math.min(
         this.comboMultiplier + 1,
         GameConfig.COMBO_MULTIPLIER_MAX
       );
       this.comboTimer = GameConfig.COMBO_TIME_WINDOW;
+      
+      // Emit combo sound event if multiplier increased
+      if (this.comboMultiplier > oldMultiplier) {
+        // Create temporary entity for combo sound
+        const comboEntity = this.world.createEntity();
+        this.world.addComponent(comboEntity, new SoundEvent('combo', this.comboMultiplier));
+      }
     } else {
       // Reset combo
       this.comboMultiplier = 1;
@@ -377,6 +399,9 @@ export class Game {
     if (this.score > this.highScore) {
       this.highScore = this.score;
       this.saveHighScore(this.highScore);
+      // Emit high score sound event
+      const highScoreEntity = this.world.createEntity();
+      this.world.addComponent(highScoreEntity, new SoundEvent('highscore'));
     }
 
     this.updateUI();
@@ -415,6 +440,10 @@ export class Game {
           invincibility.activate(powerUp.duration);
         }
       }
+      
+      // Emit power-up sound event
+      const powerUpSoundEntity = this.world.createEntity();
+      this.world.addComponent(powerUpSoundEntity, new SoundEvent('powerup'));
     }
 
     // Emit particles
@@ -502,6 +531,10 @@ export class Game {
     this.comboMultiplier = 1;
     this.comboTimer = 0;
 
+    // Emit damage sound event
+    const damageSoundEntity = this.world.createEntity();
+    this.world.addComponent(damageSoundEntity, new SoundEvent('damage'));
+
     this.updateUI();
 
     if (isDead) {
@@ -570,6 +603,10 @@ export class Game {
       newHighScoreEl.style.display = 'none';
     }
     
+    // Emit game over sound event
+    const gameOverEntity = this.world.createEntity();
+    this.world.addComponent(gameOverEntity, new SoundEvent('gameover'));
+    
     document.getElementById('gameOver').style.display = 'block';
   }
 
@@ -624,6 +661,10 @@ export class Game {
       if (e.key.toLowerCase() === 't') {
         this.togglePerformanceMonitor();
       }
+      // Toggle sound with 'M' key
+      if (e.key.toLowerCase() === 'm') {
+        this.toggleSound();
+      }
     });
 
     // Shake detection for mobile
@@ -658,6 +699,28 @@ export class Game {
 
     // Load version
     this.loadVersion();
+    
+    // Setup sound status click handler
+    const soundStatusEl = document.getElementById('soundStatus');
+    if (soundStatusEl) {
+      soundStatusEl.addEventListener('click', async () => {
+        this.toggleSound();
+
+      });
+    }
+    
+    // Initialize sound system on first click anywhere
+    document.addEventListener('click', () => {
+      if (this.soundSystem && this.soundSystem.isEnabled()) {
+        console.log('Sound system ready, state:', this.soundSystem.getState());
+        // Start background music after initialization
+        if (this.soundSystem.isEnabled()) {
+          this.soundSystem.startBackgroundMusic().catch(err => {
+            console.warn('Failed to start background music:', err);
+          });
+        }
+      }
+    }, { once: true });
   }
 
   /**
@@ -675,6 +738,31 @@ export class Game {
     }
   }
 
+  /**
+   * Toggle sound on/off
+   */
+  toggleSound() {
+    if (this.soundSystem) {
+      const enabled = this.soundSystem.toggle();
+      const soundStatusEl = document.getElementById('soundStatus');
+      if (soundStatusEl) {
+        soundStatusEl.textContent = enabled ? '🔊' : '🔇';
+        soundStatusEl.title = enabled ? 'Sound ON (Press M to mute)' : 'Sound OFF (Press M to unmute)';
+      }
+      
+      // Start/stop background music based on sound state
+      if (enabled) {
+        this.soundSystem.startBackgroundMusic().catch(err => {
+          console.warn('Failed to start background music:', err);
+        });
+      } else {
+        this.soundSystem.stopBackgroundMusic();
+      }
+      
+      console.log('Sound', enabled ? 'enabled' : 'disabled');
+    }
+  }
+
   /**
    * Handle device motion for shake detection
    * @param {DeviceMotionEvent} event
@@ -851,6 +939,9 @@ export class Game {
         const health = this.world.getComponent(this.playerEntity, Health);
         if (health && health.currentHealth < health.maxHealth) {
           health.heal(GameConfig.HEALTH_REGEN_AMOUNT);
+          // Emit health regen sound event
+          const healthRegenEntity = this.world.createEntity();
+          this.world.addComponent(healthRegenEntity, new SoundEvent('health'));
           this.updateUI();
         }
         this.healthRegenTimer = 0;

src/game/GameConfig.js

@@ -4,7 +4,7 @@
  */
 export const GameConfig = {
   // Gameplay
-  OBSTACLE_DAMAGE: 3, // Increased from 1 to balance invincibility frames and health regen
+  OBSTACLE_DAMAGE: 5, // Increased from 3 - obstacles should be more dangerous
   COIN_SCORE: 10,
   HEALTH_REGEN_INTERVAL: 10, // Heal 1 HP every 10 seconds
   HEALTH_REGEN_AMOUNT: 1,
@@ -15,7 +15,7 @@ export const GameConfig = {
   COMBO_BASE_SCORE: 10, // Base score per coin
   
   // Invincibility
-  INVINCIBILITY_DURATION: 1.5, // Seconds of invincibility after damage
+  INVINCIBILITY_DURATION: 0.8, // Reduced from 1.5 to 0.8 seconds - shorter invincibility window
   INVINCIBILITY_FLASH_RATE: 0.1, // Seconds between flash toggles
   
   // Screen Shake

src/systems/PowerUpSystem.js

@@ -1,8 +1,6 @@
 import { System } from '../ecs/System.js';
 import { PowerUp } from '../components/PowerUp.js';
 import { Transform } from '../components/Transform.js';
-import { Velocity } from '../components/Velocity.js';
-import { PlayerTag } from '../components/Tags.js';
 import { GameConfig } from '../game/GameConfig.js';
 
 /**

src/systems/SoundSystem.js

@@ -0,0 +1,584 @@
+import { System } from '../ecs/System.js';
+import { SoundEvent } from '../components/SoundEvent.js';
+
+/**
+ * SoundSystem - Lightweight sound system using Web Audio API (no external dependencies)
+ * Generates simple procedural sound effects
+ * Follows ECS pattern: processes SoundEvent components from entities
+ */
+export class SoundSystem extends System {
+  constructor() {
+    super();
+
+    /** @type {AudioContext|null} Web Audio API context */
+    this.audioContext = null;
+
+    /** @type {boolean} Whether sound is enabled */
+    this.enabled = true;
+
+    /** @type {boolean} Whether audio context is initialized */
+    this.initialized = false;
+
+    /** @type {OscillatorNode[]} Active background music oscillators */
+    this.bgMusicOscillators = [];
+
+    /** @type {GainNode|null} Background music gain node */
+    this.bgMusicGain = null;
+
+    /** @type {boolean} Whether background music is playing */
+    this.bgMusicPlaying = false;
+
+    /** @type {number} Background music volume (0-1) */
+    this.bgMusicVolume = 0.25; // Increased from 0.15 for better audibility
+
+    // Initialize on first user interaction (browser requirement)
+    this.initOnInteraction();
+  }
+
+  /**
+   * Called when system is added to world
+   */
+  init() {
+    if (this.enabled && !this.bgMusicPlaying) {
+      this.startBackgroundMusic().catch(err => {
+        console.warn('Failed to auto-start background music:', err);
+      });
+    }
+  }
+
+  /**
+   * Update - processes SoundEvent components
+   * @param {number} _deltaTime - Time since last frame (not used for sound events)
+   */
+  update(_deltaTime) {
+    // Process all SoundEvent components
+    const soundEvents = this.getEntities(SoundEvent);
+
+    for (const entityId of soundEvents) {
+      const soundEvent = this.getComponent(entityId, SoundEvent);
+
+      if (soundEvent && !soundEvent.processed) {
+        // Play the appropriate sound based on type
+        this.playSoundEvent(soundEvent);
+
+        // Mark as processed and remove component
+        soundEvent.processed = true;
+        this.world.removeComponent(entityId, SoundEvent);
+      }
+    }
+  }
+
+  /**
+   * Play a sound event
+   * @param {SoundEvent} soundEvent - The sound event to play
+   */
+  playSoundEvent(soundEvent) {
+    if (!this.enabled) return;
+
+    // All sound methods are async, handle them properly
+    const playSound = async (soundMethod) => {
+      try {
+        await soundMethod();
+      } catch (error) {
+        // Silently ignore sound errors
+      }
+    };
+
+    switch (soundEvent.type) {
+      case 'coin':
+        playSound(() => this.playCoinCollect());
+        break;
+      case 'damage':
+        playSound(() => this.playDamage());
+        break;
+      case 'powerup':
+        playSound(() => this.playPowerUp());
+        break;
+      case 'combo':
+        playSound(() => this.playCombo(soundEvent.value || 1));
+        break;
+      case 'health':
+        playSound(() => this.playHealthRegen());
+        break;
+      case 'gameover':
+        playSound(() => this.playGameOver());
+        break;
+      case 'highscore':
+        playSound(() => this.playHighScore());
+        break;
+      default:
+        console.warn('Unknown sound event type:', soundEvent.type);
+    }
+  }
+
+  /**
+   * Initialize audio context on first user interaction
+   */
+  initOnInteraction() {
+    const initAudio = async () => {
+      if (!this.initialized) {
+        try {
+          this.audioContext = new (window.AudioContext || window.webkitAudioContext)();
+          this.initialized = true;
+
+          // Resume if suspended
+          if (this.audioContext.state === 'suspended') {
+            await this.audioContext.resume();
+          }
+        } catch (error) {
+          console.warn('Web Audio API not supported:', error);
+          this.enabled = false;
+        }
+      }
+    };
+
+    // Initialize on any user interaction
+    ['click', 'touchstart', 'keydown', 'mousedown'].forEach(event => {
+      document.addEventListener(event, initAudio, { once: true });
+    });
+  }
+
+  /**
+   * Ensure audio context is initialized and resumed
+   * @returns {boolean} True if audio is ready (synchronous check)
+   */
+  ensureInitialized() {
+    if (!this.enabled) return false;
+
+    // Create audio context if it doesn't exist
+    if (!this.audioContext) {
+      try {
+        this.audioContext = new (window.AudioContext || window.webkitAudioContext)();
+        this.initialized = true;
+      } catch (error) {
+        console.warn('Failed to create audio context:', error);
+        return false;
+      }
+    }
+
+    // Try to resume if suspended (non-blocking - will resume on next interaction if needed)
+    if (this.audioContext.state === 'suspended') {
+      this.audioContext.resume().then(() => {
+        console.log('Audio context resumed');
+      }).catch(error => {
+        console.warn('Failed to resume audio context:', error);
+      });
+    }
+
+    return this.initialized && this.enabled;
+  }
+
+  /**
+   * Play a tone
+   * @param {number} frequency - Frequency in Hz
+   * @param {number} duration - Duration in seconds
+   * @param {string} type - Waveform type ('sine', 'square', 'sawtooth', 'triangle')
+   * @param {number} [volume=0.3] - Volume (0-1)
+   */
+  async playTone(frequency, duration, type = 'sine', volume = 0.3) {
+    const ready = this.ensureInitialized();
+    if (!ready || !this.audioContext) return;
+
+    try {
+      const oscillator = this.audioContext.createOscillator();
+      const gainNode = this.audioContext.createGain();
+
+      oscillator.connect(gainNode);
+      gainNode.connect(this.audioContext.destination);
+
+      oscillator.frequency.value = frequency;
+      oscillator.type = type;
+
+      // Envelope: quick attack, sustain, quick release
+      const now = this.audioContext.currentTime;
+      gainNode.gain.setValueAtTime(0, now);
+      gainNode.gain.linearRampToValueAtTime(volume, now + 0.01);
+      gainNode.gain.setValueAtTime(volume, now + duration * 0.7);
+      gainNode.gain.exponentialRampToValueAtTime(0.001, now + duration);
+
+      oscillator.start(now);
+      oscillator.stop(now + duration);
+    } catch (error) {
+      console.warn('Failed to play tone:', error);
+    }
+  }
+
+  /**
+   * Play a coin collection sound - metallic clinking like real coins
+   */
+  async playCoinCollect() {
+    // Metallic clink using multiple harmonics via playTone
+    // Main coin "clink" - high frequency
+    await this.playTone(800, 0.15, 'sine', 0.3);
+    await this.playTone(1200, 0.15, 'sine', 0.2);
+    await this.playTone(1600, 0.15, 'sine', 0.1);
+
+    // Second coin clink slightly delayed for "clinking" effect
+    setTimeout(() => {
+      if (this.enabled) {
+        this.playTone(1000, 0.1, 'sine', 0.25).catch(() => { });
+      }
+    }, 30);
+  }
+
+  /**
+   * Play a damage sound - "ouch" like human exclamation
+   */
+  async playDamage() {
+    await this.playTone(300, 0.2, 'sine', 0.4);
+    await this.playTone(600, 0.2, 'sine', 0.3);
+    await this.playTone(800, 0.2, 'sawtooth', 0.2);
+
+    // Add a quick "uh" sound at the end
+    setTimeout(() => {
+      if (this.enabled) {
+        this.playTone(250, 0.1, 'sine', 0.2).catch(() => { });
+      }
+    }, 100);
+  }
+
+  /**
+   * Play a power-up sound
+   */
+  playPowerUp() {
+    // Ascending arpeggio
+    const notes = [440, 554.37, 659.25, 783.99]; // A, C#, E, G
+    notes.forEach((freq, i) => {
+      setTimeout(() => {
+        if (this.enabled) {
+          this.playTone(freq, 0.15, 'sine', 0.25).catch(() => { });
+        }
+      }, i * 80);
+    });
+  }
+
+  /**
+   * Play a combo sound (higher multiplier = more notes)
+   * @param {number} multiplier - Combo multiplier
+   */
+  playCombo(multiplier) {
+    const baseFreq = 440;
+    const notes = Math.min(multiplier, 5);
+
+    for (let i = 0; i < notes; i++) {
+      setTimeout(() => {
+        if (this.enabled) {
+          const freq = baseFreq * (1 + i * 0.2);
+          this.playTone(freq, 0.1, 'sine', 0.15).catch(() => { });
+        }
+      }, i * 50);
+    }
+  }
+
+  /**
+   * Play a health regeneration sound
+   */
+  playHealthRegen() {
+    // Gentle ascending tone
+    this.playTone(330, 0.2, 'sine', 0.15).catch(() => { });
+    setTimeout(() => {
+      if (this.enabled) {
+        this.playTone(392, 0.2, 'sine', 0.15).catch(() => { });
+      }
+    }, 100);
+  }
+
+  /**
+   * Play a game over sound
+   */
+  playGameOver() {
+    // Descending sad tone
+    const notes = [440, 392, 349, 294]; // A, G, F, D
+    notes.forEach((freq, i) => {
+      setTimeout(() => {
+        if (this.enabled) {
+          this.playTone(freq, 0.3, 'sine', 0.3).catch(() => { });
+        }
+      }, i * 150);
+    });
+  }
+
+  /**
+   * Play a new high score sound
+   */
+  playHighScore() {
+    // Triumphant ascending scale
+    const notes = [523.25, 659.25, 783.99, 987.77]; // C, E, G, B
+    notes.forEach((freq, i) => {
+      setTimeout(() => {
+        if (this.enabled) {
+          this.playTone(freq, 0.2, 'sine', 0.3).catch(() => { });
+        }
+      }, i * 100);
+    });
+  }
+
+  /**
+   * Toggle sound on/off
+   * @returns {boolean} New enabled state
+   */
+  toggle() {
+    this.enabled = !this.enabled;
+    return this.enabled;
+  }
+
+  /**
+   * Set sound enabled state
+   * @param {boolean} enabled
+   */
+  setEnabled(enabled) {
+    this.enabled = enabled;
+  }
+
+  /**
+   * Check if sound is enabled
+   * @returns {boolean}
+   */
+  isEnabled() {
+    return this.enabled;
+  }
+
+  /**
+   * Get audio context state for debugging
+   * @returns {string} Audio context state
+   */
+  getState() {
+    if (!this.audioContext) return 'not initialized';
+    return this.audioContext.state;
+  }
+
+  /**
+   * Test sound - plays a simple tone to verify audio works
+   */
+  async testSound() {
+    console.log('Testing sound system...');
+    console.log('Audio context state:', this.getState());
+    await this.playTone(440, 0.2, 'sine', 0.5);
+    console.log('Test sound played');
+  }
+
+  /**
+   * Start background music - animated looping OST
+   */
+  async startBackgroundMusic() {
+    if (this.bgMusicPlaying) {
+      console.log('Background music already playing');
+      return;
+    }
+
+    const ready = this.ensureInitialized();
+    if (!ready || !this.audioContext) {
+      console.warn('Cannot start background music: audio context not ready, state:', this.getState());
+      return;
+    }
+
+    try {
+      this.bgMusicPlaying = true;
+      console.log('Starting background music, audio context state:', this.audioContext.state);
+
+      // Create gain node for background music volume control
+      this.bgMusicGain = this.audioContext.createGain();
+      this.bgMusicGain.gain.value = this.bgMusicVolume * 0.5;
+      this.bgMusicGain.connect(this.audioContext.destination);
+
+      // Electronic/EDM style music
+      // Simple chord progression: C - Am - F - G (I - vi - IV - V - classic electronic progression)
+      const chordProgression = [
+        [130.81, 164.81, 196], // C major (C, E, G)
+        [220, 261.63, 329.63], // Am (A, C, E)
+        [174.61, 220, 261.63], // F major (F, A, C)
+        [196, 246.94, 293.66]  // G major (G, B, D)
+      ];
+
+      // Electronic melody notes (higher octave, pentatonic for catchy hook)
+      const melodyNotes = [523.25, 587.33, 659.25, 698.46, 783.99, 880, 987.77, 1046.5]; // C5 to C6 - bright electronic range
+
+      // Bass line for electronic feel (lower octave)
+      const bassNotes = [65.41, 73.42, 82.41, 87.31, 98, 110, 123.47]; // C2 to B2
+
+      const playChord = (chord, startTime, duration) => {
+        chord.forEach((freq, index) => {
+          const osc = this.audioContext.createOscillator();
+          const gain = this.audioContext.createGain();
+
+          // Use sawtooth for electronic/analog synth feel
+          osc.type = 'sawtooth';
+          osc.frequency.value = freq;
+          osc.connect(gain);
+          gain.connect(this.bgMusicGain);
+
+          // Very bright, energetic attack for happy feel
+          gain.gain.setValueAtTime(0, startTime);
+          gain.gain.linearRampToValueAtTime(0.5, startTime + 0.1); // Very fast, bright attack
+          gain.gain.setValueAtTime(0.5, startTime + duration - 0.2);
+          gain.gain.linearRampToValueAtTime(0, startTime + duration);
+
+          osc.start(startTime);
+          osc.stop(startTime + duration);
+
+          this.bgMusicOscillators.push(osc);
+        });
+      };
+
+      const playMelody = (note, startTime, duration) => {
+        const osc = this.audioContext.createOscillator();
+        const gain = this.audioContext.createGain();
+
+        osc.type = 'square'; // Square wave for electronic lead
+        osc.frequency.value = note;
+        osc.connect(gain);
+        gain.connect(this.bgMusicGain);
+
+        // Very energetic, bouncy attack for happy melody
+        gain.gain.setValueAtTime(0, startTime);
+        gain.gain.linearRampToValueAtTime(0.4, startTime + 0.05); // Very quick, bright attack
+        gain.gain.setValueAtTime(0.4, startTime + duration - 0.05);
+        gain.gain.linearRampToValueAtTime(0, startTime + duration);
+
+        osc.start(startTime);
+        osc.stop(startTime + duration);
+
+        this.bgMusicOscillators.push(osc);
+      };
+
+      // Electronic bass line
+      const playBass = (note, startTime, duration) => {
+        const osc = this.audioContext.createOscillator();
+        const gain = this.audioContext.createGain();
+
+        osc.type = 'square'; // Square wave for electronic bass
+        osc.frequency.value = note;
+        osc.connect(gain);
+        gain.connect(this.bgMusicGain);
+
+        // Punchy bass envelope
+        gain.gain.setValueAtTime(0, startTime);
+        gain.gain.linearRampToValueAtTime(0.4, startTime + 0.02);
+        gain.gain.setValueAtTime(0.4, startTime + duration - 0.05);
+        gain.gain.exponentialRampToValueAtTime(0.001, startTime + duration);
+
+        osc.start(startTime);
+        osc.stop(startTime + duration);
+
+        this.bgMusicOscillators.push(osc);
+      };
+
+      // Loop function - creates 8 second loop (fast electronic tempo)
+      const loopDuration = 8; // seconds - fast electronic tempo
+      let nextLoopTime = this.audioContext.currentTime;
+
+      const scheduleLoop = () => {
+        if (!this.bgMusicPlaying || !this.audioContext) return;
+
+        const startTime = nextLoopTime;
+
+        // Play chord progression (4 chords, 2 seconds each - fast electronic tempo)
+        chordProgression.forEach((chord, chordIndex) => {
+          const chordStart = startTime + (chordIndex * 2);
+          playChord(chord, chordStart, 1.9);
+        });
+
+        // Electronic bass line (pulsing rhythm)
+        const bassPattern = [
+          { note: bassNotes[0], time: 0, duration: 0.3 },    // C - kick
+          { note: bassNotes[0], time: 0.5, duration: 0.2 },   // C
+          { note: bassNotes[2], time: 1.0, duration: 0.3 },  // E
+          { note: bassNotes[0], time: 1.5, duration: 0.2 },  // C
+          { note: bassNotes[3], time: 2.0, duration: 0.3 }, // F
+          { note: bassNotes[0], time: 2.5, duration: 0.2 },  // C
+          { note: bassNotes[4], time: 3.0, duration: 0.3 },  // G
+          { note: bassNotes[0], time: 3.5, duration: 0.2 },  // C
+          { note: bassNotes[2], time: 4.0, duration: 0.3 },  // E
+          { note: bassNotes[0], time: 4.5, duration: 0.2 },  // C
+          { note: bassNotes[3], time: 5.0, duration: 0.3 },  // F
+          { note: bassNotes[0], time: 5.5, duration: 0.2 },  // C
+          { note: bassNotes[4], time: 6.0, duration: 0.3 },  // G
+          { note: bassNotes[0], time: 6.5, duration: 0.2 },  // C
+          { note: bassNotes[2], time: 7.0, duration: 0.3 }   // E
+        ];
+
+        bassPattern.forEach(({ note, time, duration }) => {
+          playBass(note, startTime + time, duration);
+        });
+
+        // Play melody over chords (simpler pattern)
+        const melodyPattern = [
+          { note: melodyNotes[0], time: 0.5, duration: 1 },
+          { note: melodyNotes[2], time: 2, duration: 1 },
+          { note: melodyNotes[4], time: 4.5, duration: 1 },
+          { note: melodyNotes[3], time: 6, duration: 1 },
+          { note: melodyNotes[5], time: 8.5, duration: 1.5 },
+          { note: melodyNotes[4], time: 10.5, duration: 1 },
+          { note: melodyNotes[2], time: 12, duration: 1.5 },
+          { note: melodyNotes[0], time: 14, duration: 1.5 }
+        ];
+
+        melodyPattern.forEach(({ note, time, duration }) => {
+          playMelody(note, startTime + time, duration);
+        });
+
+        // Schedule next loop
+        nextLoopTime += loopDuration;
+
+        // Schedule next loop before current one ends (schedule 2 seconds before end)
+        const timeUntilNext = (nextLoopTime - this.audioContext.currentTime) * 1000 - 2000;
+
+        if (timeUntilNext > 0) {
+          setTimeout(() => {
+            if (this.bgMusicPlaying && this.audioContext) {
+              scheduleLoop();
+            }
+          }, timeUntilNext);
+        } else {
+          // If we're behind, schedule immediately
+          scheduleLoop();
+        }
+      };
+
+      // Start first loop immediately
+      scheduleLoop();
+
+      console.log('Background music started, audio context state:', this.audioContext.state);
+      console.log('Background music volume:', this.bgMusicVolume);
+    } catch (error) {
+      console.warn('Failed to start background music:', error);
+      this.bgMusicPlaying = false;
+    }
+  }
+
+  /**
+   * Stop background music
+   */
+  stopBackgroundMusic() {
+    this.bgMusicPlaying = false;
+
+    // Stop all oscillators
+    this.bgMusicOscillators.forEach(osc => {
+      try {
+        osc.stop();
+      } catch (e) {
+        // Oscillator might already be stopped
+      }
+    });
+    this.bgMusicOscillators = [];
+
+    if (this.bgMusicGain) {
+      this.bgMusicGain.disconnect();
+      this.bgMusicGain = null;
+    }
+
+    console.log('Background music stopped');
+  }
+
+  /**
+   * Set background music volume
+   * @param {number} volume - Volume (0-1)
+   */
+  setBackgroundMusicVolume(volume) {
+    this.bgMusicVolume = Math.max(0, Math.min(1, volume));
+    if (this.bgMusicGain) {
+      this.bgMusicGain.gain.value = this.bgMusicVolume;
+    }
+  }
+}
+