remove unused code

src/ui/flutter_app/lib/l10n/intl_en.arb

@@ -430,9 +430,9 @@
     "@difficulty": {
         "description": "Difficulty"
     },
-    "playSounds": "Sound effects",
+    "gameSettings": "Game settings",
-    "@playSounds": {
+    "@gameSettings": {
-        "description": "Sound effects"
+        "description": "Settings to change the behaviour of the game."
     },
     "playSoundsInTheGame": "Play sounds in the game",
     "@playSoundsInTheGame": {

src/ui/flutter_app/lib/models/preferences.dart

@@ -52,7 +52,8 @@ class Preferences {
     this.considerMobility = true,
     @Deprecated("we won't export the developer settings anymore. People should use the EnvironmentConfig.devMode")
         this.developerMode = false,
-    this.experimentsEnabled = false,
+    @Deprecated("use [EnvironmentConfig.devMode] instead")
+        this.experimentsEnabled = false,
   });
 
   @HiveField(0)
@@ -98,6 +99,7 @@ class Preferences {
   )
   final bool developerMode;
   @HiveField(19)
+  @Deprecated("use [EnvironmentConfig.devMode] instead")
   final bool experimentsEnabled;
 
   /// encodes a Json style map into a [Preferences] object

src/ui/flutter_app/lib/screens/game_settings/game_settings_page.dart

@@ -23,7 +23,6 @@ import 'package:flutter/material.dart';
 import 'package:hive_flutter/hive_flutter.dart' show Box;
 import 'package:sanmill/generated/intl/l10n.dart';
 import 'package:sanmill/models/preferences.dart';
-import 'package:sanmill/screens/env_page.dart';
 import 'package:sanmill/services/environment_config.dart';
 import 'package:sanmill/services/storage/storage.dart';
 import 'package:sanmill/shared/custom_drawer/custom_drawer.dart';
@@ -141,13 +140,6 @@ class GameSettingsPage extends StatelessWidget {
     debugPrint("$_tag screenReaderSupport: $value");
   }
 
-  void _setExperimentsEnabled(Preferences _preferences, bool value) {
-    LocalDatabaseService.preferences =
-        _preferences.copyWith(experimentsEnabled: value);
-
-    debugPrint("$_tag experimentsEnabled: $value");
-  }
-
   Column _buildPrefs(BuildContext context, Box<Preferences> prefBox, _) {
     final Preferences _preferences = prefBox.get(
       LocalDatabaseService.preferencesKey,
@@ -156,9 +148,14 @@ class GameSettingsPage extends StatelessWidget {
 
     final _widowsSettings = [
       const CustomSpacer(),
-      Text(S.of(context).playSounds, style: AppTheme.settingsHeaderStyle),
+      Text(S.of(context).gameSettings, style: AppTheme.settingsHeaderStyle),
       SettingsCard(
         children: <Widget>[
+          SettingsSwitchListTile(
+            value: _preferences.isAutoRestart,
+            onChanged: (val) => _setIsAutoRestart(_preferences, val),
+            titleString: S.of(context).isAutoRestart,
+          ),
           SettingsSwitchListTile(
             value: _preferences.toneEnabled,
             onChanged: (val) => _setTone(_preferences, val),
@@ -173,39 +170,6 @@ class GameSettingsPage extends StatelessWidget {
       ),
     ];
 
-    final _developerSettings = [
-      const CustomSpacer(),
-      Text(S.of(context).forDevelopers, style: AppTheme.settingsHeaderStyle),
-      SettingsCard(
-        children: <Widget>[
-          SettingsSwitchListTile(
-            value: EnvironmentConfig.devMode,
-            onChanged: (_) {},
-            titleString: S.of(context).developerMode,
-          ),
-          SettingsSwitchListTile(
-            value: _preferences.experimentsEnabled,
-            onChanged: (val) => _setExperimentsEnabled(_preferences, val),
-            titleString: S.of(context).experiments,
-          ),
-          SettingsSwitchListTile(
-            value: _preferences.isAutoRestart,
-            onChanged: (val) => _setIsAutoRestart(_preferences, val),
-            titleString: S.of(context).isAutoRestart,
-          ),
-          SettingsListTile(
-            titleString: S.of(context).environmentVariables,
-            onTap: () => Navigator.push(
-              context,
-              MaterialPageRoute(
-                builder: (_) => const EnvironmentVariablesPage(),
-              ),
-            ),
-          ),
-        ],
-      ),
-    ];
-
     return Column(
       crossAxisAlignment: CrossAxisAlignment.start,
       children: [
@@ -289,7 +253,6 @@ class GameSettingsPage extends StatelessWidget {
             ),
           ],
         ),
-        if (EnvironmentConfig.devMode) ..._developerSettings,
       ],
     );
   }

src/ui/flutter_app/lib/screens/rule_settings/rule_settings_page.dart

@@ -20,6 +20,7 @@ import 'package:flutter/material.dart';
 import 'package:hive_flutter/hive_flutter.dart' show Box;
 import 'package:sanmill/generated/intl/l10n.dart';
 import 'package:sanmill/models/rules.dart';
+import 'package:sanmill/services/environment_config.dart';
 import 'package:sanmill/services/storage/storage.dart';
 import 'package:sanmill/shared/custom_drawer/custom_drawer.dart';
 import 'package:sanmill/shared/custom_spacer.dart';
@@ -269,21 +270,20 @@ class RuleSettingsPage extends StatelessWidget {
         Text(S.of(context).moving, style: AppTheme.settingsHeaderStyle),
         SettingsCard(
           children: <Widget>[
-            if (LocalDatabaseService.preferences.experimentsEnabled)
+            if (EnvironmentConfig.devMode)
               SettingsSwitchListTile(
                 value: _rules.mayMoveInPlacingPhase,
                 onChanged: (val) =>
                     _setMayMoveInPlacingPhase(context, _rules, val),
                 titleString: S.of(context).mayMoveInPlacingPhase,
                 subtitleString: S.of(context).mayMoveInPlacingPhase_Detail,
-              )
-            else
-              SettingsSwitchListTile(
-                value: _rules.isDefenderMoveFirst,
-                onChanged: (val) => _setIsDefenderMoveFirst(_rules, val),
-                titleString: S.of(context).isDefenderMoveFirst,
-                subtitleString: S.of(context).isDefenderMoveFirst_Detail,
               ),
+            SettingsSwitchListTile(
+              value: _rules.isDefenderMoveFirst,
+              onChanged: (val) => _setIsDefenderMoveFirst(_rules, val),
+              titleString: S.of(context).isDefenderMoveFirst,
+              subtitleString: S.of(context).isDefenderMoveFirst_Detail,
+            ),
             SettingsSwitchListTile(
               value: _rules.isLoseButNotChangeSideWhenNoWay,
               onChanged: (val) =>