Add game_template (#1180)

Adds a template / sample for games built in Flutter, with all the bells and whistles, like ads, in-app purchases, audio, main menu, settings, and so on.

Co-authored-by: Parker Lougheed
Co-authored-by: Shams Zakhour

game_template/lib/src/level_selection/level_selection_screen.dart

@@ -0,0 +1,71 @@
+// Copyright 2022, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:provider/provider.dart';
+
+import '../audio/audio_controller.dart';
+import '../audio/sounds.dart';
+import '../player_progress/player_progress.dart';
+import '../style/palette.dart';
+import '../style/responsive_screen.dart';
+import 'levels.dart';
+
+class LevelSelectionScreen extends StatelessWidget {
+  const LevelSelectionScreen({Key? key}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    final palette = context.watch<Palette>();
+    final playerProgress = context.watch<PlayerProgress>();
+
+    return Scaffold(
+      backgroundColor: palette.backgroundLevelSelection,
+      body: ResponsiveScreen(
+        squarishMainArea: Column(
+          children: [
+            const Padding(
+              padding: EdgeInsets.all(16),
+              child: Center(
+                child: Text(
+                  'Select level',
+                  style:
+                      TextStyle(fontFamily: 'Permanent Marker', fontSize: 30),
+                ),
+              ),
+            ),
+            const SizedBox(height: 50),
+            Expanded(
+              child: ListView(
+                children: [
+                  for (final level in gameLevels)
+                    ListTile(
+                      enabled: playerProgress.highestLevelReached >=
+                          level.number - 1,
+                      onTap: () {
+                        final audioController = context.read<AudioController>();
+                        audioController.playSfx(SfxType.buttonTap);
+
+                        GoRouter.of(context)
+                            .go('/play/session/${level.number}');
+                      },
+                      leading: Text(level.number.toString()),
+                      title: Text('Level #${level.number}'),
+                    )
+                ],
+              ),
+            ),
+          ],
+        ),
+        rectangularMenuArea: ElevatedButton(
+          onPressed: () {
+            GoRouter.of(context).pop();
+          },
+          child: const Text('Back'),
+        ),
+      ),
+    );
+  }
+}

game_template/lib/src/level_selection/levels.dart

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+// Copyright 2022, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+const gameLevels = [
+  GameLevel(
+    number: 1,
+    difficulty: 5,
+    // TODO: When ready, change these achievement IDs.
+    // You configure this in App Store Connect.
+    achievementIdIOS: 'first_win',
+    // You get this string when you configure an achievement in Play Console.
+    achievementIdAndroid: 'NhkIwB69ejkMAOOLDb',
+  ),
+  GameLevel(
+    number: 2,
+    difficulty: 42,
+  ),
+  GameLevel(
+    number: 3,
+    difficulty: 100,
+    achievementIdIOS: 'finished',
+    achievementIdAndroid: 'CdfIhE96aspNWLGSQg',
+  ),
+];
+
+class GameLevel {
+  final int number;
+
+  final int difficulty;
+
+  /// The achievement to unlock when the level is finished, if any.
+  final String? achievementIdIOS;
+
+  final String? achievementIdAndroid;
+
+  bool get awardsAchievement => achievementIdAndroid != null;
+
+  const GameLevel({
+    required this.number,
+    required this.difficulty,
+    this.achievementIdIOS,
+    this.achievementIdAndroid,
+  }) : assert(
+            (achievementIdAndroid != null && achievementIdIOS != null) ||
+                (achievementIdAndroid == null && achievementIdIOS == null),
+            'Either both iOS and Android achievement ID must be provided, '
+            'or none');
+}