feat(app): 오디오 및 설정 시스템 통합

- AudioService 앱 수준 초기화 및 dispose
- 게임 화면에서 오디오/설정 연동

lib/data/game_text_l10n.dart

@@ -1792,3 +1792,97 @@ String get uiLoading {
   if (isJapaneseLocale) return '読み込み中...';
   return 'Loading...';
 }
+
+// ============================================================================
+// 설정 화면 텍스트
+// ============================================================================
+
+String get uiSettings {
+  if (isKoreanLocale) return '설정';
+  if (isJapaneseLocale) return '設定';
+  return 'Settings';
+}
+
+String get uiTheme {
+  if (isKoreanLocale) return '테마';
+  if (isJapaneseLocale) return 'テーマ';
+  return 'Theme';
+}
+
+String get uiThemeLight {
+  if (isKoreanLocale) return '라이트';
+  if (isJapaneseLocale) return 'ライト';
+  return 'Light';
+}
+
+String get uiThemeDark {
+  if (isKoreanLocale) return '다크';
+  if (isJapaneseLocale) return 'ダーク';
+  return 'Dark';
+}
+
+String get uiThemeSystem {
+  if (isKoreanLocale) return '시스템';
+  if (isJapaneseLocale) return 'システム';
+  return 'System';
+}
+
+String get uiLanguage {
+  if (isKoreanLocale) return '언어';
+  if (isJapaneseLocale) return '言語';
+  return 'Language';
+}
+
+String get uiSound {
+  if (isKoreanLocale) return '사운드';
+  if (isJapaneseLocale) return 'サウンド';
+  return 'Sound';
+}
+
+String get uiBgmVolume {
+  if (isKoreanLocale) return 'BGM 볼륨';
+  if (isJapaneseLocale) return 'BGM音量';
+  return 'BGM Volume';
+}
+
+String get uiSfxVolume {
+  if (isKoreanLocale) return '효과음 볼륨';
+  if (isJapaneseLocale) return '効果音音量';
+  return 'SFX Volume';
+}
+
+String get uiAnimationSpeed {
+  if (isKoreanLocale) return '애니메이션 속도';
+  if (isJapaneseLocale) return 'アニメーション速度';
+  return 'Animation Speed';
+}
+
+String get uiSpeedSlow {
+  if (isKoreanLocale) return '느림';
+  if (isJapaneseLocale) return '遅い';
+  return 'Slow';
+}
+
+String get uiSpeedNormal {
+  if (isKoreanLocale) return '보통';
+  if (isJapaneseLocale) return '普通';
+  return 'Normal';
+}
+
+String get uiSpeedFast {
+  if (isKoreanLocale) return '빠름';
+  if (isJapaneseLocale) return '速い';
+  return 'Fast';
+}
+
+String get uiAbout {
+  if (isKoreanLocale) return '정보';
+  if (isJapaneseLocale) return '情報';
+  return 'About';
+}
+
+String get uiAboutDescription {
+  if (isKoreanLocale) return 'Progress Quest 6.4를 Flutter로 재구현한 오프라인 싱글플레이어 RPG입니다.';
+  if (isJapaneseLocale) return 'Progress Quest 6.4をFlutterで再実装したオフラインシングルプレイヤーRPGです。';
+  return 'An offline single-player RPG reimplementation of Progress Quest 6.4 in Flutter.';
+}

lib/src/app.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 
 import 'package:askiineverdie/data/game_text_l10n.dart' as game_l10n;
 import 'package:askiineverdie/l10n/app_localizations.dart';
+import 'package:askiineverdie/src/core/audio/audio_service.dart';
 import 'package:askiineverdie/src/core/engine/game_mutations.dart';
 import 'package:askiineverdie/src/core/engine/progress_service.dart';
 import 'package:askiineverdie/src/core/engine/reward_service.dart';
@@ -30,6 +31,7 @@ class _AskiiNeverDieAppState extends State<AskiiNeverDieApp> {
   late final GameSessionController _controller;
   late final NotificationService _notificationService;
   late final SettingsRepository _settingsRepository;
+  late final AudioService _audioService;
   bool _isCheckingSave = true;
   bool _hasSave = false;
   ThemeMode _themeMode = ThemeMode.system;
@@ -51,9 +53,11 @@ class _AskiiNeverDieAppState extends State<AskiiNeverDieApp> {
     );
     _notificationService = NotificationService();
     _settingsRepository = SettingsRepository();
+    _audioService = AudioService(settingsRepository: _settingsRepository);
 
-    // 초기 설정 로드
+    // 초기 설정 및 오디오 서비스 로드
     _loadSettings();
+    _audioService.init();
     // 세이브 파일 존재 여부 확인
     _checkForExistingSave();
   }
@@ -87,6 +91,7 @@ class _AskiiNeverDieAppState extends State<AskiiNeverDieApp> {
   void dispose() {
     _controller.dispose();
     _notificationService.dispose();
+    _audioService.dispose();
     super.dispose();
   }
 

lib/src/core/audio/audio_service.dart

@@ -0,0 +1,228 @@
+import 'package:just_audio/just_audio.dart';
+
+import 'package:askiineverdie/src/core/storage/settings_repository.dart';
+
+/// 게임 오디오 서비스
+///
+/// BGM과 SFX를 관리하며, 설정과 연동하여 볼륨을 조절합니다.
+class AudioService {
+  AudioService({SettingsRepository? settingsRepository})
+      : _settingsRepository = settingsRepository ?? SettingsRepository();
+
+  final SettingsRepository _settingsRepository;
+
+  // BGM 플레이어
+  AudioPlayer? _bgmPlayer;
+
+  // SFX 플레이어 풀 (동시 재생 지원)
+  final List<AudioPlayer> _sfxPlayers = [];
+  static const int _maxSfxPlayers = 5;
+
+  // 현재 볼륨
+  double _bgmVolume = 0.7;
+  double _sfxVolume = 0.8;
+
+  // 현재 재생 중인 BGM
+  String? _currentBgm;
+
+  // 초기화 여부
+  bool _initialized = false;
+
+  /// 서비스 초기화
+  Future<void> init() async {
+    if (_initialized) return;
+
+    // 설정에서 볼륨 불러오기
+    _bgmVolume = await _settingsRepository.loadBgmVolume();
+    _sfxVolume = await _settingsRepository.loadSfxVolume();
+
+    // BGM 플레이어 초기화
+    _bgmPlayer = AudioPlayer();
+    await _bgmPlayer!.setLoopMode(LoopMode.one);
+    await _bgmPlayer!.setVolume(_bgmVolume);
+
+    // SFX 플레이어 풀 초기화
+    for (var i = 0; i < _maxSfxPlayers; i++) {
+      final player = AudioPlayer();
+      await player.setVolume(_sfxVolume);
+      _sfxPlayers.add(player);
+    }
+
+    _initialized = true;
+  }
+
+  /// BGM 재생
+  ///
+  /// [name]은 assets/audio/bgm/ 폴더 내 파일명 (확장자 제외)
+  /// 예: playBgm('battle') → assets/audio/bgm/battle.wav 또는 battle.mp3
+  Future<void> playBgm(String name) async {
+    if (!_initialized) await init();
+    if (_currentBgm == name) return; // 이미 재생 중
+
+    try {
+      _currentBgm = name;
+      // WAV 먼저 시도, 실패하면 MP3 시도
+      try {
+        await _bgmPlayer!.setAsset('assets/audio/bgm/$name.wav');
+      } catch (_) {
+        await _bgmPlayer!.setAsset('assets/audio/bgm/$name.mp3');
+      }
+      await _bgmPlayer!.play();
+    } catch (e) {
+      // 파일이 없으면 무시 (개발 중 에셋 미추가 상태)
+      _currentBgm = null;
+    }
+  }
+
+  /// BGM 정지
+  Future<void> stopBgm() async {
+    if (!_initialized) return;
+
+    await _bgmPlayer!.stop();
+    _currentBgm = null;
+  }
+
+  /// BGM 일시정지
+  Future<void> pauseBgm() async {
+    if (!_initialized) return;
+    await _bgmPlayer!.pause();
+  }
+
+  /// BGM 재개
+  Future<void> resumeBgm() async {
+    if (!_initialized) return;
+    if (_currentBgm != null) {
+      await _bgmPlayer!.play();
+    }
+  }
+
+  /// SFX 재생
+  ///
+  /// [name]은 assets/audio/sfx/ 폴더 내 파일명 (확장자 제외)
+  /// 예: playSfx('attack') → assets/audio/sfx/attack.wav 또는 attack.mp3
+  Future<void> playSfx(String name) async {
+    if (!_initialized) await init();
+    if (_sfxVolume == 0) return; // 볼륨이 0이면 재생 안함
+
+    // 사용 가능한 플레이어 찾기
+    AudioPlayer? availablePlayer;
+    for (final player in _sfxPlayers) {
+      if (!player.playing) {
+        availablePlayer = player;
+        break;
+      }
+    }
+
+    // 모든 플레이어가 사용 중이면 첫 번째 플레이어 재사용
+    availablePlayer ??= _sfxPlayers.first;
+
+    try {
+      // WAV 먼저 시도, 실패하면 MP3 시도
+      try {
+        await availablePlayer.setAsset('assets/audio/sfx/$name.wav');
+      } catch (_) {
+        await availablePlayer.setAsset('assets/audio/sfx/$name.mp3');
+      }
+      await availablePlayer.seek(Duration.zero);
+      await availablePlayer.play();
+    } catch (e) {
+      // 파일이 없으면 무시
+    }
+  }
+
+  /// BGM 볼륨 설정 (0.0 ~ 1.0)
+  Future<void> setBgmVolume(double volume) async {
+    _bgmVolume = volume.clamp(0.0, 1.0);
+    if (_initialized && _bgmPlayer != null) {
+      await _bgmPlayer!.setVolume(_bgmVolume);
+    }
+    await _settingsRepository.saveBgmVolume(_bgmVolume);
+  }
+
+  /// SFX 볼륨 설정 (0.0 ~ 1.0)
+  Future<void> setSfxVolume(double volume) async {
+    _sfxVolume = volume.clamp(0.0, 1.0);
+    if (_initialized) {
+      for (final player in _sfxPlayers) {
+        await player.setVolume(_sfxVolume);
+      }
+    }
+    await _settingsRepository.saveSfxVolume(_sfxVolume);
+  }
+
+  /// 현재 BGM 볼륨
+  double get bgmVolume => _bgmVolume;
+
+  /// 현재 SFX 볼륨
+  double get sfxVolume => _sfxVolume;
+
+  /// 현재 재생 중인 BGM
+  String? get currentBgm => _currentBgm;
+
+  /// 서비스 정리
+  Future<void> dispose() async {
+    await _bgmPlayer?.dispose();
+    for (final player in _sfxPlayers) {
+      await player.dispose();
+    }
+    _sfxPlayers.clear();
+    _initialized = false;
+  }
+}
+
+/// BGM 타입 열거형
+enum BgmType {
+  /// 마을/상점 BGM
+  town,
+
+  /// 일반 전투 BGM
+  battle,
+
+  /// 보스 전투 BGM
+  boss,
+
+  /// 레벨업/퀘스트 완료 팡파레
+  victory,
+}
+
+/// SFX 타입 열거형
+enum SfxType {
+  /// 공격
+  attack,
+
+  /// 피격
+  hit,
+
+  /// 스킬 사용
+  skill,
+
+  /// 아이템 획득
+  item,
+
+  /// UI 클릭
+  click,
+
+  /// 레벨업
+  levelUp,
+
+  /// 퀘스트 완료
+  questComplete,
+}
+
+/// BgmType을 파일명으로 변환
+extension BgmTypeExtension on BgmType {
+  String get fileName => name;
+}
+
+/// SfxType을 파일명으로 변환
+extension SfxTypeExtension on SfxType {
+  String get fileName => switch (this) {
+    SfxType.attack => 'attack',
+    SfxType.hit => 'hit',
+    SfxType.skill => 'skill',
+    SfxType.item => 'item',
+    SfxType.click => 'click',
+    SfxType.levelUp => 'level_up',
+    SfxType.questComplete => 'quest_complete',
+  };
+}

lib/src/core/storage/settings_repository.dart

@@ -3,10 +3,13 @@ import 'package:shared_preferences/shared_preferences.dart';
 
 /// 앱 설정 저장소 (SharedPreferences 기반)
 ///
-/// 테마, 언어 등 사용자 설정을 로컬에 저장
+/// 테마, 언어, 사운드 등 사용자 설정을 로컬에 저장
 class SettingsRepository {
   static const _keyThemeMode = 'theme_mode';
   static const _keyLocale = 'locale';
+  static const _keyBgmVolume = 'bgm_volume';
+  static const _keySfxVolume = 'sfx_volume';
+  static const _keyAnimationSpeed = 'animation_speed';
 
   SharedPreferences? _prefs;
 
@@ -49,4 +52,40 @@ class SettingsRepository {
     await init();
     return _prefs!.getString(_keyLocale);
   }
+
+  /// BGM 볼륨 저장 (0.0 ~ 1.0)
+  Future<void> saveBgmVolume(double volume) async {
+    await init();
+    await _prefs!.setDouble(_keyBgmVolume, volume.clamp(0.0, 1.0));
+  }
+
+  /// BGM 볼륨 불러오기 (기본값: 0.7)
+  Future<double> loadBgmVolume() async {
+    await init();
+    return _prefs!.getDouble(_keyBgmVolume) ?? 0.7;
+  }
+
+  /// SFX 볼륨 저장 (0.0 ~ 1.0)
+  Future<void> saveSfxVolume(double volume) async {
+    await init();
+    await _prefs!.setDouble(_keySfxVolume, volume.clamp(0.0, 1.0));
+  }
+
+  /// SFX 볼륨 불러오기 (기본값: 0.8)
+  Future<double> loadSfxVolume() async {
+    await init();
+    return _prefs!.getDouble(_keySfxVolume) ?? 0.8;
+  }
+
+  /// 애니메이션 속도 저장 (0.5 ~ 2.0, 1.0이 기본)
+  Future<void> saveAnimationSpeed(double speed) async {
+    await init();
+    await _prefs!.setDouble(_keyAnimationSpeed, speed.clamp(0.5, 2.0));
+  }
+
+  /// 애니메이션 속도 불러오기 (기본값: 1.0)
+  Future<double> loadAnimationSpeed() async {
+    await init();
+    return _prefs!.getDouble(_keyAnimationSpeed) ?? 1.0;
+  }
 }

lib/src/features/game/game_play_screen.dart

@@ -31,6 +31,8 @@ import 'package:askiineverdie/src/features/game/widgets/potion_inventory_panel.d
 import 'package:askiineverdie/src/features/game/widgets/task_progress_panel.dart';
 import 'package:askiineverdie/src/features/game/widgets/active_buff_panel.dart';
 import 'package:askiineverdie/src/features/game/layouts/mobile_carousel_layout.dart';
+import 'package:askiineverdie/src/features/settings/settings_screen.dart';
+import 'package:askiineverdie/src/core/storage/settings_repository.dart';
 
 /// 게임 진행 화면 (Main.dfm 기반 3패널 레이아웃)
 ///
@@ -463,51 +465,17 @@ class _GamePlayScreenState extends State<GamePlayScreen>
     return platform == TargetPlatform.iOS || platform == TargetPlatform.android;
   }
 
-  /// 현재 언어명 가져오기
-  String _getCurrentLanguageName() {
-    final locale = game_l10n.currentGameLocale;
-    if (locale == 'ko') return game_l10n.languageKorean;
-    if (locale == 'ja') return game_l10n.languageJapanese;
-    return game_l10n.languageEnglish;
-  }
-
-  /// 언어 선택 다이얼로그 표시
-  void _showLanguageDialog(BuildContext context) {
-    showDialog<void>(
-      context: context,
-      builder: (context) => AlertDialog(
-        title: Text(game_l10n.menuLanguage),
-        content: Column(
-          mainAxisSize: MainAxisSize.min,
-          children: [
-            _buildLanguageOption(context, 'en', game_l10n.languageEnglish),
-            _buildLanguageOption(context, 'ko', game_l10n.languageKorean),
-            _buildLanguageOption(context, 'ja', game_l10n.languageJapanese),
-          ],
-        ),
-      ),
-    );
-  }
-
-  Widget _buildLanguageOption(
-    BuildContext context,
-    String locale,
-    String label,
-  ) {
-    final isSelected = game_l10n.currentGameLocale == locale;
-    return ListTile(
-      leading: Icon(
-        isSelected ? Icons.radio_button_checked : Icons.radio_button_unchecked,
-        color: isSelected ? Theme.of(context).colorScheme.primary : null,
-      ),
-      title: Text(
-        label,
-        style: TextStyle(
-          fontWeight: isSelected ? FontWeight.bold : FontWeight.normal,
-        ),
-      ),
-      onTap: () async {
-        Navigator.pop(context); // 다이얼로그 닫기
+  /// 설정 화면 표시
+  void _showSettingsScreen(BuildContext context) {
+    final settingsRepo = SettingsRepository();
+    SettingsScreen.show(
+      context,
+      settingsRepository: settingsRepo,
+      currentThemeMode: widget.currentThemeMode,
+      onThemeModeChange: (mode) {
+        widget.onThemeModeChange?.call(mode);
+      },
+      onLocaleChange: (locale) async {
         // 안전한 언어 변경: 전체 화면 재생성
         final navigator = Navigator.of(this.context);
         await widget.controller.pause(saveOnStop: true);
@@ -698,11 +666,11 @@ class _GamePlayScreenState extends State<GamePlayScreen>
                   onPressed: () => widget.controller.loop?.cheatCompletePlot(),
                 ),
               ],
-              // 언어 변경 버튼
-              TextButton.icon(
-                onPressed: () => _showLanguageDialog(context),
-                icon: const Icon(Icons.language, size: 18),
-                label: Text(_getCurrentLanguageName()),
+              // 설정 버튼
+              IconButton(
+                icon: const Icon(Icons.settings),
+                tooltip: game_l10n.uiSettings,
+                onPressed: () => _showSettingsScreen(context),
               ),
             ],
           ),

lib/src/features/settings/settings_screen.dart

@@ -0,0 +1,412 @@
+import 'package:flutter/material.dart';
+
+import 'package:askiineverdie/data/game_text_l10n.dart' as game_l10n;
+import 'package:askiineverdie/src/core/storage/settings_repository.dart';
+
+/// 통합 설정 화면
+///
+/// 언어, 테마, 사운드, 애니메이션 속도 등 모든 설정을 한 곳에서 관리
+class SettingsScreen extends StatefulWidget {
+  const SettingsScreen({
+    super.key,
+    required this.settingsRepository,
+    required this.currentThemeMode,
+    required this.onThemeModeChange,
+    this.onLocaleChange,
+  });
+
+  final SettingsRepository settingsRepository;
+  final ThemeMode currentThemeMode;
+  final void Function(ThemeMode mode) onThemeModeChange;
+  final void Function(String locale)? onLocaleChange;
+
+  @override
+  State<SettingsScreen> createState() => _SettingsScreenState();
+
+  /// 설정 화면을 모달 바텀시트로 표시
+  static Future<void> show(
+    BuildContext context, {
+    required SettingsRepository settingsRepository,
+    required ThemeMode currentThemeMode,
+    required void Function(ThemeMode mode) onThemeModeChange,
+    void Function(String locale)? onLocaleChange,
+  }) {
+    return showModalBottomSheet<void>(
+      context: context,
+      isScrollControlled: true,
+      useSafeArea: true,
+      builder: (context) => DraggableScrollableSheet(
+        initialChildSize: 0.7,
+        minChildSize: 0.5,
+        maxChildSize: 0.95,
+        expand: false,
+        builder: (context, scrollController) => SettingsScreen(
+          settingsRepository: settingsRepository,
+          currentThemeMode: currentThemeMode,
+          onThemeModeChange: onThemeModeChange,
+          onLocaleChange: onLocaleChange,
+        ),
+      ),
+    );
+  }
+}
+
+class _SettingsScreenState extends State<SettingsScreen> {
+  double _bgmVolume = 0.7;
+  double _sfxVolume = 0.8;
+  double _animationSpeed = 1.0;
+  bool _isLoading = true;
+
+  @override
+  void initState() {
+    super.initState();
+    _loadSettings();
+  }
+
+  Future<void> _loadSettings() async {
+    final bgm = await widget.settingsRepository.loadBgmVolume();
+    final sfx = await widget.settingsRepository.loadSfxVolume();
+    final speed = await widget.settingsRepository.loadAnimationSpeed();
+
+    if (mounted) {
+      setState(() {
+        _bgmVolume = bgm;
+        _sfxVolume = sfx;
+        _animationSpeed = speed;
+        _isLoading = false;
+      });
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+
+    if (_isLoading) {
+      return const Center(child: CircularProgressIndicator());
+    }
+
+    return Container(
+      decoration: BoxDecoration(
+        color: theme.scaffoldBackgroundColor,
+        borderRadius: const BorderRadius.vertical(top: Radius.circular(16)),
+      ),
+      child: Column(
+        children: [
+          // 핸들 바
+          Container(
+            margin: const EdgeInsets.only(top: 8),
+            width: 40,
+            height: 4,
+            decoration: BoxDecoration(
+              color: theme.colorScheme.onSurface.withValues(alpha: 0.3),
+              borderRadius: BorderRadius.circular(2),
+            ),
+          ),
+          // 헤더
+          Padding(
+            padding: const EdgeInsets.all(16),
+            child: Row(
+              children: [
+                Icon(Icons.settings, color: theme.colorScheme.primary),
+                const SizedBox(width: 8),
+                Text(
+                  game_l10n.uiSettings,
+                  style: theme.textTheme.titleLarge,
+                ),
+                const Spacer(),
+                IconButton(
+                  icon: const Icon(Icons.close),
+                  onPressed: () => Navigator.of(context).pop(),
+                ),
+              ],
+            ),
+          ),
+          const Divider(height: 1),
+          // 설정 목록
+          Expanded(
+            child: ListView(
+              padding: const EdgeInsets.all(16),
+              children: [
+                // 테마 설정
+                _buildSectionTitle(game_l10n.uiTheme),
+                _buildThemeSelector(),
+                const SizedBox(height: 24),
+
+                // 언어 설정
+                _buildSectionTitle(game_l10n.uiLanguage),
+                _buildLanguageSelector(),
+                const SizedBox(height: 24),
+
+                // 사운드 설정
+                _buildSectionTitle(game_l10n.uiSound),
+                _buildVolumeSlider(
+                  label: game_l10n.uiBgmVolume,
+                  value: _bgmVolume,
+                  icon: Icons.music_note,
+                  onChanged: (value) {
+                    setState(() => _bgmVolume = value);
+                    widget.settingsRepository.saveBgmVolume(value);
+                  },
+                ),
+                const SizedBox(height: 8),
+                _buildVolumeSlider(
+                  label: game_l10n.uiSfxVolume,
+                  value: _sfxVolume,
+                  icon: Icons.volume_up,
+                  onChanged: (value) {
+                    setState(() => _sfxVolume = value);
+                    widget.settingsRepository.saveSfxVolume(value);
+                  },
+                ),
+                const SizedBox(height: 24),
+
+                // 애니메이션 속도
+                _buildSectionTitle(game_l10n.uiAnimationSpeed),
+                _buildAnimationSpeedSlider(),
+                const SizedBox(height: 24),
+
+                // 정보
+                _buildSectionTitle(game_l10n.uiAbout),
+                _buildAboutCard(),
+              ],
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+
+  Widget _buildSectionTitle(String title) {
+    return Padding(
+      padding: const EdgeInsets.only(bottom: 8),
+      child: Text(
+        title,
+        style: Theme.of(context).textTheme.titleMedium?.copyWith(
+          fontWeight: FontWeight.bold,
+        ),
+      ),
+    );
+  }
+
+  Widget _buildThemeSelector() {
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.all(8),
+        child: Row(
+          children: [
+            _buildThemeOption(
+              icon: Icons.light_mode,
+              label: game_l10n.uiThemeLight,
+              mode: ThemeMode.light,
+            ),
+            _buildThemeOption(
+              icon: Icons.dark_mode,
+              label: game_l10n.uiThemeDark,
+              mode: ThemeMode.dark,
+            ),
+            _buildThemeOption(
+              icon: Icons.brightness_auto,
+              label: game_l10n.uiThemeSystem,
+              mode: ThemeMode.system,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _buildThemeOption({
+    required IconData icon,
+    required String label,
+    required ThemeMode mode,
+  }) {
+    final isSelected = widget.currentThemeMode == mode;
+    final theme = Theme.of(context);
+
+    return Expanded(
+      child: InkWell(
+        onTap: () => widget.onThemeModeChange(mode),
+        borderRadius: BorderRadius.circular(8),
+        child: Container(
+          padding: const EdgeInsets.symmetric(vertical: 12),
+          decoration: BoxDecoration(
+            color: isSelected
+                ? theme.colorScheme.primaryContainer
+                : Colors.transparent,
+            borderRadius: BorderRadius.circular(8),
+          ),
+          child: Column(
+            children: [
+              Icon(
+                icon,
+                color: isSelected
+                    ? theme.colorScheme.primary
+                    : theme.colorScheme.onSurface,
+              ),
+              const SizedBox(height: 4),
+              Text(
+                label,
+                style: TextStyle(
+                  fontSize: 12,
+                  fontWeight: isSelected ? FontWeight.bold : FontWeight.normal,
+                  color: isSelected
+                      ? theme.colorScheme.primary
+                      : theme.colorScheme.onSurface,
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+
+  Widget _buildLanguageSelector() {
+    final currentLocale = game_l10n.currentGameLocale;
+    final languages = [
+      ('en', 'English', '🇺🇸'),
+      ('ko', '한국어', '🇰🇷'),
+      ('ja', '日本語', '🇯🇵'),
+    ];
+
+    return Card(
+      child: Column(
+        children: languages.map((lang) {
+          final isSelected = currentLocale == lang.$1;
+          return ListTile(
+            leading: Text(lang.$3, style: const TextStyle(fontSize: 24)),
+            title: Text(lang.$2),
+            trailing: isSelected
+                ? Icon(Icons.check, color: Theme.of(context).colorScheme.primary)
+                : null,
+            onTap: () {
+              game_l10n.setGameLocale(lang.$1);
+              widget.settingsRepository.saveLocale(lang.$1);
+              widget.onLocaleChange?.call(lang.$1);
+              setState(() {});
+            },
+          );
+        }).toList(),
+      ),
+    );
+  }
+
+  Widget _buildVolumeSlider({
+    required String label,
+    required double value,
+    required IconData icon,
+    required void Function(double) onChanged,
+  }) {
+    final theme = Theme.of(context);
+    final percentage = (value * 100).round();
+
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+        child: Row(
+          children: [
+            Icon(
+              value == 0 ? Icons.volume_off : icon,
+              color: theme.colorScheme.primary,
+            ),
+            const SizedBox(width: 12),
+            Expanded(
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Row(
+                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                    children: [
+                      Text(label),
+                      Text('$percentage%'),
+                    ],
+                  ),
+                  Slider(
+                    value: value,
+                    onChanged: onChanged,
+                    divisions: 10,
+                  ),
+                ],
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _buildAnimationSpeedSlider() {
+    final theme = Theme.of(context);
+    final speedLabel = switch (_animationSpeed) {
+      <= 0.6 => game_l10n.uiSpeedSlow,
+      >= 1.4 => game_l10n.uiSpeedFast,
+      _ => game_l10n.uiSpeedNormal,
+    };
+
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+        child: Row(
+          children: [
+            Icon(Icons.speed, color: theme.colorScheme.primary),
+            const SizedBox(width: 12),
+            Expanded(
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Row(
+                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                    children: [
+                      Text(game_l10n.uiAnimationSpeed),
+                      Text(speedLabel),
+                    ],
+                  ),
+                  Slider(
+                    value: _animationSpeed,
+                    min: 0.5,
+                    max: 2.0,
+                    divisions: 6,
+                    onChanged: (value) {
+                      setState(() => _animationSpeed = value);
+                      widget.settingsRepository.saveAnimationSpeed(value);
+                    },
+                  ),
+                ],
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _buildAboutCard() {
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.all(16),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Text(
+              'ASCII NEVER DIE',
+              style: Theme.of(context).textTheme.titleMedium,
+            ),
+            const SizedBox(height: 8),
+            Text(
+              game_l10n.uiAboutDescription,
+              style: Theme.of(context).textTheme.bodySmall,
+            ),
+            const SizedBox(height: 8),
+            Text(
+              'v1.0.0',
+              style: Theme.of(context).textTheme.bodySmall?.copyWith(
+                color: Theme.of(context).colorScheme.outline,
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

macos/Flutter/GeneratedPluginRegistrant.swift

@@ -5,10 +5,14 @@
 import FlutterMacOS
 import Foundation
 
+import audio_session
+import just_audio
 import path_provider_foundation
 import shared_preferences_foundation
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
+  AudioSessionPlugin.register(with: registry.registrar(forPlugin: "AudioSessionPlugin"))
+  JustAudioPlugin.register(with: registry.registrar(forPlugin: "JustAudioPlugin"))
   PathProviderPlugin.register(with: registry.registrar(forPlugin: "PathProviderPlugin"))
   SharedPreferencesPlugin.register(with: registry.registrar(forPlugin: "SharedPreferencesPlugin"))
 }

pubspec.lock

@@ -9,6 +9,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.13.0"
+  audio_session:
+    dependency: transitive
+    description:
+      name: audio_session
+      sha256: "2b7fff16a552486d078bfc09a8cde19f426dc6d6329262b684182597bec5b1ac"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.1.25"
   boolean_selector:
     dependency: transitive
     description:
@@ -41,6 +49,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.19.1"
+  crypto:
+    dependency: transitive
+    description:
+      name: crypto
+      sha256: c8ea0233063ba03258fbcf2ca4d6dadfefe14f02fab57702265467a19f27fadf
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.0.7"
   cupertino_icons:
     dependency: "direct main"
     description:
@@ -73,6 +89,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "7.0.1"
+  fixnum:
+    dependency: transitive
+    description:
+      name: fixnum
+      sha256: b6dc7065e46c974bc7c5f143080a6764ec7a4be6da1285ececdc37be96de53be
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.1"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -109,6 +133,30 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.20.2"
+  just_audio:
+    dependency: "direct main"
+    description:
+      name: just_audio
+      sha256: f978d5b4ccea08f267dae0232ec5405c1b05d3f3cd63f82097ea46c015d5c09e
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.9.46"
+  just_audio_platform_interface:
+    dependency: transitive
+    description:
+      name: just_audio_platform_interface
+      sha256: "2532c8d6702528824445921c5ff10548b518b13f808c2e34c2fd54793b999a6a"
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.6.0"
+  just_audio_web:
+    dependency: transitive
+    description:
+      name: just_audio_web
+      sha256: "6ba8a2a7e87d57d32f0f7b42856ade3d6a9fbe0f1a11fabae0a4f00bb73f0663"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.4.16"
   leak_tracker:
     dependency: transitive
     description:
@@ -237,6 +285,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.8"
+  rxdart:
+    dependency: transitive
+    description:
+      name: rxdart
+      sha256: "5c3004a4a8dbb94bd4bf5412a4def4acdaa12e12f269737a5751369e12d1a962"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.28.0"
   shared_preferences:
     dependency: "direct main"
     description:
@@ -330,6 +386,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.4.1"
+  synchronized:
+    dependency: transitive
+    description:
+      name: synchronized
+      sha256: c254ade258ec8282947a0acbbc90b9575b4f19673533ee46f2f6e9b3aeefd7c0
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.4.0"
   term_glyph:
     dependency: transitive
     description:
@@ -346,6 +410,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.7.6"
+  typed_data:
+    dependency: transitive
+    description:
+      name: typed_data
+      sha256: f9049c039ebfeb4cf7a7104a675823cd72dba8297f264b6637062516699fa006
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.4.0"
+  uuid:
+    dependency: transitive
+    description:
+      name: uuid
+      sha256: a11b666489b1954e01d992f3d601b1804a33937b5a8fe677bd26b8a9f96f96e8
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.5.2"
   vector_math:
     dependency: transitive
     description:

pubspec.yaml

@@ -37,6 +37,7 @@ dependencies:
   intl: ^0.20.2
   path_provider: ^2.1.4
   shared_preferences: ^2.3.1
+  just_audio: ^0.9.42
 
 dev_dependencies:
   flutter_test:
@@ -65,6 +66,8 @@ flutter:
   # To add assets to your application, add an assets section, like this:
   assets:
     - assets/
+    - assets/audio/bgm/
+    - assets/audio/sfx/
 
   # An image asset can refer to one or more resolution-specific "variants", see
   # https://flutter.dev/to/resolution-aware-images