diff --git a/Mlaumcherb.Client.Avalonia/Config.cs b/Mlaumcherb.Client.Avalonia/Config.cs
index e0b11c3..470b88b 100644
--- a/Mlaumcherb.Client.Avalonia/Config.cs
+++ b/Mlaumcherb.Client.Avalonia/Config.cs
@@ -20,7 +20,7 @@ public record Config
     public bool redirect_game_output { get; set; } = false;
     public string? last_launched_version { get; set; }
     public int max_parallel_downloads { get; set; } = 16;
-    public VersionCatalogProps[] version_catalogs { get; set; } =
+    public GameVersionCatalogProps[] version_catalogs { get; set; } =
     [
         new() { name = "Mojang", url = "https://piston-meta.mojang.com/mc/game/version_manifest_v2.json" },
         new() { name = "Тимериховое", url = "https://timerix.ddns.net/minecraft/catalog.json" }
@@ -31,10 +31,10 @@ public record Config
     
     public static Config LoadFromFile()
     {
-        LauncherApp.Logger.LogInfo(nameof(Config), $"loading config from file '{_filePath}'");
+        LauncherApp.Logger.LogDebug(nameof(Config), $"loading config from file '{_filePath}'");
         if(!File.Exists(_filePath))
         {
-            LauncherApp.Logger.LogInfo(nameof(Config), "file doesn't exist");
+            LauncherApp.Logger.LogDebug(nameof(Config), "file doesn't exist");
             return new Config();
         }
 
@@ -67,7 +67,7 @@ public record Config
 
     public void SaveToFile()
     {
-        LauncherApp.Logger.LogInfo(nameof(Config), $"saving config to file '{_filePath}'");
+        LauncherApp.Logger.LogDebug(nameof(Config), $"saving config to file '{_filePath}'");
         var text = JsonConvert.SerializeObject(this, Formatting.Indented);
         File.WriteAllText(_filePath, text);
         LauncherApp.Logger.LogDebug(nameof(Config), $"config has been saved: {text}");
diff --git a/Mlaumcherb.Client.Avalonia/GameVersion.cs b/Mlaumcherb.Client.Avalonia/GameVersion.cs
index eded8b7..203bbce 100644
--- a/Mlaumcherb.Client.Avalonia/GameVersion.cs
+++ b/Mlaumcherb.Client.Avalonia/GameVersion.cs
@@ -7,15 +7,14 @@ using Mlaumcherb.Client.Avalonia.классы;
 using Mlaumcherb.Client.Avalonia.сеть;
 using Mlaumcherb.Client.Avalonia.сеть.TaskFactories;
 using Mlaumcherb.Client.Avalonia.холопы;
-using Newtonsoft.Json.Linq;
 using static Mlaumcherb.Client.Avalonia.холопы.PathHelper;
 
 namespace Mlaumcherb.Client.Avalonia;
 
 public class GameVersion
 {
-    private readonly GameVersionProps _props;
-    public string Name => _props.Name;
+    private readonly InstalledGameVersionProps _props;
+    public string Id => _props.Id;
     public IOPath WorkingDirectory { get; }
 
     private IOPath JavaExecutableFilePath;
@@ -27,69 +26,10 @@ public class GameVersion
     private CancellationTokenSource? _gameCts;
     private CommandTask<CommandResult>? _commandTask;
 
-    public static Task<List<GameVersionProps>> GetAllVersionsAsync()
-    {
-        var propsList = new List<GameVersionProps>();
-        
-        // local descriptors
-        Directory.Create(GetVersionsDir());
-        foreach (IOPath subdir in Directory.GetDirectories(GetVersionsDir()))
-        {
-            string name = subdir.LastName().ToString();
-            var d = new GameVersionProps(name);
-            if(!File.Exists(d.LocalDescriptorPath))
-                throw new Exception("Can't find version descriptor file in directory '{subdir}'. Rename it as directory name.");
-            propsList.Add(d);
-        }
-        
-        // reverse sort
-        propsList.Sort((a, b) => b.CompareTo(a));
-        return Task.FromResult(propsList);
-    }
-
-    public static async Task<GameVersion> CreateFromPropsAsync(GameVersionProps props, bool checkHash)
-    {
-        //TODO: refresh version descriptor from server
-        if (!File.Exists(props.LocalDescriptorPath))
-        {
-            if (props.RemoteProps is null)
-                throw new NullReferenceException("can't download game version descriptor '"
-                                                 + props.Name + "', because RemoteDescriptorUrl is null");
-            await NetworkHelper.DownloadFile(props.RemoteProps.url, props.LocalDescriptorPath);
-        }
-
-        return new GameVersion(props);
-    }
-
-    private GameVersion(GameVersionProps props)
+    internal GameVersion(InstalledGameVersionProps props, GameVersionDescriptor descriptor)
     {
         _props = props;
-        
-        string descriptorText = File.ReadAllText(props.LocalDescriptorPath);
-        JObject descriptorRaw =  JObject.Parse(descriptorText);
-        
-        // Descriptors can inherit from other descriptors.
-        // For example, 1.12.2-forge-14.23.5.2860 inherits from 1.12.2
-        if (descriptorRaw.TryGetValue("inheritsFrom", out var v))
-        {
-            string parentDescriptorId = v.Value<string>() 
-                        ?? throw new Exception("inheritsFrom is null");
-            LauncherApp.Logger.LogInfo(Name, $"merging descriptor '{parentDescriptorId}' with '{Name}'");
-            IOPath parentDescriptorPath = GetVersionDescriptorPath(parentDescriptorId);
-            if (!File.Exists(parentDescriptorPath))
-                throw new Exception($"Версия '{Name} требует установить версию '{parentDescriptorId}'");
-            string parentDescriptorText = File.ReadAllText(parentDescriptorPath);
-            JObject parentDescriptorRaw = JObject.Parse(parentDescriptorText);
-            parentDescriptorRaw.Merge(descriptorRaw,
-                new JsonMergeSettings { MergeArrayHandling = MergeArrayHandling.Concat });
-            descriptorRaw = parentDescriptorRaw;
-            // removing dependency
-            descriptorRaw.Remove("inheritsFrom");
-            File.WriteAllText(props.LocalDescriptorPath, descriptorRaw.ToString());
-        }
-
-        _descriptor = descriptorRaw.ToObject<GameVersionDescriptor>()
-                      ?? throw new Exception($"can't parse descriptor file '{props.LocalDescriptorPath}'");
+        _descriptor = descriptor;
         _javaArgs = new JavaArguments(_descriptor);
         _gameArgs = new GameArguments(_descriptor);
         _libraries = new Libraries(_descriptor);
@@ -97,30 +37,28 @@ public class GameVersion
         JavaExecutableFilePath = GetJavaExecutablePath(_descriptor.javaVersion.component, LauncherApp.Config.debug);
     }
 
-    public async Task UpdateFiles(bool checkHashes, Action<NetworkTask> networkTaskCreatedCallback)
+    public async Task Download(bool update, Action<NetworkTask> networkTaskCreatedCallback)
     {
-        LauncherApp.Logger.LogInfo(Name, $"started updating version {Name}");
+        
+        
+        LauncherApp.Logger.LogInfo(Id, $"started updating version {Id}");
         
         List<INetworkTaskFactory> taskFactories =
         [
             new AssetsDownloadTaskFactory(_descriptor),
             new LibrariesDownloadTaskFactory(_descriptor, _libraries),
         ];
-        if (LauncherApp.Config.download_java)
-        {
+        if (LauncherApp.Config.download_java) 
             taskFactories.Add(new JavaDownloadTaskFactory(_descriptor));
-        }
-        if (_descriptor.modpack != null)
-        {
+        if (_descriptor.modpack != null) 
             taskFactories.Add(new ModpackDownloadTaskFactory(_descriptor));
-        }
-        // has to be downloaded last because it is used by GameVersionProps to check if version is installed
+        // has to be downloaded last because it is used to check if version is installed
         taskFactories.Add(new VersionJarDownloadTaskFactory(_descriptor));
         
         var networkTasks = new List<NetworkTask>();
         for (int i = 0; i < taskFactories.Count; i++)
         {
-            var nt = await taskFactories[i].CreateAsync(checkHashes);
+            var nt = await taskFactories[i].CreateAsync(update);
             if (nt != null)
             {
                 networkTasks.Add(nt);
@@ -142,8 +80,8 @@ public class GameVersion
             await res.CopyToAsync(file);
         }
         
-        _props.IsDownloaded = true;
-        LauncherApp.Logger.LogInfo(Name, $"finished updating version {Name}");
+        _props.IsInstalled = true;
+        LauncherApp.Logger.LogInfo(Id, $"finished updating version {Id}");
     }
     
     //minecraft player uuid explanation
@@ -224,23 +162,23 @@ public class GameVersion
                 .WithStandardOutputPipe(PipeTarget.ToDelegate(LogGameOut))
                 .WithStandardErrorPipe(PipeTarget.ToDelegate(LogGameError));
         }
-        LauncherApp.Logger.LogInfo(Name, "launching the game");
-        LauncherApp.Logger.LogDebug(Name, "java: " + command.TargetFilePath);
-        LauncherApp.Logger.LogDebug(Name, "working_dir: " + command.WorkingDirPath);
-        LauncherApp.Logger.LogDebug(Name, "arguments: \n\t" + argsList.MergeToString("\n\t"));
+        LauncherApp.Logger.LogInfo(Id, "launching the game");
+        LauncherApp.Logger.LogDebug(Id, "java: " + command.TargetFilePath);
+        LauncherApp.Logger.LogDebug(Id, "working_dir: " + command.WorkingDirPath);
+        LauncherApp.Logger.LogDebug(Id, "arguments: \n\t" + argsList.MergeToString("\n\t"));
         _gameCts = new();
         _commandTask = command.ExecuteAsync(_gameCts.Token);
         var result = await _commandTask;
-        LauncherApp.Logger.LogInfo(Name, $"game exited with code {result.ExitCode}");
+        LauncherApp.Logger.LogInfo(Id, $"game exited with code {result.ExitCode}");
     }
 
     private void LogGameOut(string line)
     {
-        LauncherApp.Logger.LogInfo(Name, line);
+        LauncherApp.Logger.LogInfo(Id, line);
     }
     private void LogGameError(string line)
     {
-        LauncherApp.Logger.LogWarn(Name, line);
+        LauncherApp.Logger.LogWarn(Id, line);
     }
     
     public void Close()
@@ -249,5 +187,5 @@ public class GameVersion
     }
 
 
-    public override string ToString() => Name;
+    public override string ToString() => Id;
 }
\ No newline at end of file
diff --git a/Mlaumcherb.Client.Avalonia/LauncherLogger.cs b/Mlaumcherb.Client.Avalonia/LauncherLogger.cs
index fcd8c83..ba8ca55 100644
--- a/Mlaumcherb.Client.Avalonia/LauncherLogger.cs
+++ b/Mlaumcherb.Client.Avalonia/LauncherLogger.cs
@@ -10,6 +10,7 @@ public class LauncherLogger : ILogger
     public LauncherLogger()
     {
         _fileLogger = new FileLogger(LogsDirectory, "млаумчерб");
+        _fileLogger.DebugLogEnabled = true;
         ILogger[] loggers = 
         [
             _fileLogger,
@@ -54,7 +55,11 @@ public class LauncherLogger : ILogger
     public bool DebugLogEnabled
     {
         get => _compositeLogger.DebugLogEnabled;
-        set => _compositeLogger.DebugLogEnabled = value;
+        set
+        {
+            _compositeLogger.DebugLogEnabled = value;
+            _fileLogger.DebugLogEnabled = true;
+        }
     }
 
     public bool InfoLogEnabled
diff --git a/Mlaumcherb.Client.Avalonia/Mlaumcherb.Client.Avalonia.csproj b/Mlaumcherb.Client.Avalonia/Mlaumcherb.Client.Avalonia.csproj
index 8db2004..ffdc793 100644
--- a/Mlaumcherb.Client.Avalonia/Mlaumcherb.Client.Avalonia.csproj
+++ b/Mlaumcherb.Client.Avalonia/Mlaumcherb.Client.Avalonia.csproj
@@ -13,6 +13,8 @@
         <AssemblyName>млаумчерб</AssemblyName>
         <Configurations>Release;Debug</Configurations>
         <Platforms>x64</Platforms>
+        <!-- AXAML resource has no public constructor -->
+        <NoWarn>AVLN3001</NoWarn>
     </PropertyGroup>
 
     <ItemGroup>
diff --git a/Mlaumcherb.Client.Avalonia/зримое/VersionItemView.axaml b/Mlaumcherb.Client.Avalonia/зримое/GameVersionItemView.axaml
similarity index 84%
rename from Mlaumcherb.Client.Avalonia/зримое/VersionItemView.axaml
rename to Mlaumcherb.Client.Avalonia/зримое/GameVersionItemView.axaml
index be8ee04..a564ac2 100644
--- a/Mlaumcherb.Client.Avalonia/зримое/VersionItemView.axaml
+++ b/Mlaumcherb.Client.Avalonia/зримое/GameVersionItemView.axaml
@@ -4,7 +4,7 @@
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
              xmlns:local="clr-namespace:Mlaumcherb.Client.Avalonia"
              mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
-             x:Class="Mlaumcherb.Client.Avalonia.зримое.VersionItemView"
+             x:Class="Mlaumcherb.Client.Avalonia.зримое.GameVersionItemView"
              Padding="2">
     <TextBlock Name="text" Background="Transparent"/>
 </UserControl>
diff --git a/Mlaumcherb.Client.Avalonia/зримое/GameVersionItemView.axaml.cs b/Mlaumcherb.Client.Avalonia/зримое/GameVersionItemView.axaml.cs
new file mode 100644
index 0000000..b3aa5e3
--- /dev/null
+++ b/Mlaumcherb.Client.Avalonia/зримое/GameVersionItemView.axaml.cs
@@ -0,0 +1,48 @@
+using Avalonia.Controls;
+using Avalonia.Media;
+using Avalonia.Threading;
+using Mlaumcherb.Client.Avalonia.классы;
+
+namespace Mlaumcherb.Client.Avalonia.зримое;
+
+public abstract partial class GameVersionItemView : ListBoxItem
+{
+    private static readonly SolidColorBrush _avaliableColor = new(Color.FromRgb(30, 130, 40));
+    private static readonly SolidColorBrush _unavaliableColor = new(Color.FromRgb(170, 70, 70));
+
+    protected GameVersionItemView(string name, bool initialStatus)
+    {
+        InitializeComponent();
+        text.Text = name;
+        UpdateBackground(initialStatus);
+    }
+
+    protected void UpdateBackground(bool isInstalled)
+    {
+        Dispatcher.UIThread.Invoke(() => Background = isInstalled ? _avaliableColor : _unavaliableColor);
+    }
+}
+
+// Background changes when props status changes
+public class InstalledGameVersionItemView : GameVersionItemView
+{
+    public readonly InstalledGameVersionProps Props;
+    
+    public InstalledGameVersionItemView(InstalledGameVersionProps props) : base(props.Id, props.IsInstalled)
+    {
+        Props = props;
+        props.StatusChanged += UpdateBackground;
+    }
+}
+
+// Background is set once by checking if the version is present in InstalledVersionsCatalog
+public class RemoteGameVersionItemView : GameVersionItemView
+{
+    public readonly RemoteVersionDescriptorProps Props;
+    
+    public RemoteGameVersionItemView(RemoteVersionDescriptorProps props) 
+        : base(props.id, LauncherApp.InstalledVersionCatalog.versions.ContainsKey(props.id))
+    {
+        Props = props;
+    }
+}
\ No newline at end of file
diff --git a/Mlaumcherb.Client.Avalonia/зримое/LauncherApp.axaml b/Mlaumcherb.Client.Avalonia/зримое/LauncherApp.axaml
index 680e6c5..5b3640d 100644
--- a/Mlaumcherb.Client.Avalonia/зримое/LauncherApp.axaml
+++ b/Mlaumcherb.Client.Avalonia/зримое/LauncherApp.axaml
@@ -25,6 +25,10 @@
             <Setter Property="MinWidth" Value="50"/>
         </Style>
         
+        <Style Selector="Button.button_dark">
+            <Setter Property="Background" Value="#65656070"/>
+        </Style>
+        
         <Style Selector="Border.menu_separator">
             <Setter Property="Background" Value="#ff505050"/>
             <Setter Property="Width" Value="1"/>
diff --git a/Mlaumcherb.Client.Avalonia/зримое/LauncherApp.axaml.cs b/Mlaumcherb.Client.Avalonia/зримое/LauncherApp.axaml.cs
index 9404307..655c4c4 100644
--- a/Mlaumcherb.Client.Avalonia/зримое/LauncherApp.axaml.cs
+++ b/Mlaumcherb.Client.Avalonia/зримое/LauncherApp.axaml.cs
@@ -1,13 +1,15 @@
 using Avalonia;
 using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Markup.Xaml;
+using Mlaumcherb.Client.Avalonia.классы;
 
 namespace Mlaumcherb.Client.Avalonia.зримое;
 
 public class LauncherApp : Application
 {
     public static LauncherLogger Logger = new();
-    public static Config Config = new();
+    public static Config Config = null!;
+    public static InstalledVersionCatalog InstalledVersionCatalog = null!;
     
     public override void Initialize()
     {
@@ -21,6 +23,8 @@ public class LauncherApp : Application
         {
             File.WriteAllText("launcher_profiles.json", "{}");
         }
+
+        InstalledVersionCatalog = InstalledVersionCatalog.Load();
     }
 
     public override void OnFrameworkInitializationCompleted()
diff --git a/Mlaumcherb.Client.Avalonia/зримое/MainWindow.axaml b/Mlaumcherb.Client.Avalonia/зримое/MainWindow.axaml
index bcdf2a9..937b397 100644
--- a/Mlaumcherb.Client.Avalonia/зримое/MainWindow.axaml
+++ b/Mlaumcherb.Client.Avalonia/зримое/MainWindow.axaml
@@ -34,20 +34,30 @@
                     <ScrollViewer Grid.Row="0" 
                               HorizontalScrollBarVisibility="Disabled"
                               VerticalScrollBarVisibility="Auto">
-                        <StackPanel Margin="10" Spacing="10">
-                            <TextBlock>Версия:</TextBlock>
-                            <ComboBox Name="InstalledVersionComboBox"/>
+                        <StackPanel Margin="10" Spacing="6">
+                            <TextBlock>Ник:</TextBlock>
+                            <TextBox Background="Transparent"
+                                     Text="{Binding #window.PlayerName}"/>
+                            
+                            <TextBlock>Версия игры:</TextBlock>
+                            <ComboBox Name="InstalledVersionCatalogComboBox"/>
+                            <Button Name="RescanInstalledVersionsButton" 
+                                    Click="RescanInstalledVersionsButton_OnClick"
+                                    Classes="button_dark">
+                                Обновить список
+                            </Button>
                             <Button Name="DeleteVersionButton" 
-                                    Click="DeleteVersionButton_OnClick">
+                                    Click="DeleteVersionButton_OnClick"
+                                    Classes="button_dark">
                                 Удалить версию
                             </Button>
                             
                             <Expander Header="Добавление версий"
                                       BorderThickness="1" BorderBrush="Gray"
                                       Padding="4">
-                                <StackPanel>
+                                <StackPanel Spacing="6">
                                     <TextBlock>Источник:</TextBlock>
-                                    <ComboBox Name="VersionCatalogComboBox"/>
+                                    <ComboBox Name="RemoteVersionCatalogComboBox"/>
                                     <WrapPanel>
                                         <CheckBox Name="ReleaseVersionTypeCheckBox" IsChecked="True">релиз</CheckBox>
                                         <CheckBox Name="SnapshotVersionTypeCheckBox">снапшот</CheckBox>
@@ -55,22 +65,20 @@
                                         <CheckBox Name="OtherVersionTypeAlphaCheckBox">другое</CheckBox>
                                     </WrapPanel>
                                     <Button Name="SearchVersionsButton"
-                                            Click="SearchVersionsButton_OnClick">
+                                            Click="SearchVersionsButton_OnClick"
+                                            Classes="button_dark">
                                         Поиск
                                     </Button>
                                     <TextBlock>Доступные версии:</TextBlock>
-                                    <ComboBox Name="VersionCatalogItemsComboBox"/>
+                                    <ComboBox Name="RemoteVersionCatalogItemsComboBox"/>
                                     <Button Name="AddVersionButton" IsEnabled="False"
-                                        Click="AddVersionButton_OnClick">
+                                        Click="AddVersionButton_OnClick"
+                                        Classes="button_dark">
                                         Добавить
                                     </Button>
                                 </StackPanel>
                             </Expander>
                             
-                            <TextBlock>Ник:</TextBlock>
-                            <TextBox Background="Transparent"
-                                     Text="{Binding #window.PlayerName}"/>
-                            
                             <TextBlock>
                                 <Run>Выделенная память:</Run>
                                 <TextBox Background="Transparent" Padding="0"
@@ -84,8 +92,8 @@
                                     Value="{Binding #window.MemoryLimit}">
                             </Slider>
                             
-                            <CheckBox IsChecked="{Binding #window.CheckGameFiles}">
-                                Проверять файлы игры
+                            <CheckBox IsChecked="{Binding #window.UpdateGameFiles}">
+                                Проверить файлы игры
                             </CheckBox>
                             <CheckBox IsChecked="{Binding #window.EnableJavaDownload}">
                                 Скачивать джаву
diff --git a/Mlaumcherb.Client.Avalonia/зримое/MainWindow.axaml.cs b/Mlaumcherb.Client.Avalonia/зримое/MainWindow.axaml.cs
index cc1f343..8151568 100644
--- a/Mlaumcherb.Client.Avalonia/зримое/MainWindow.axaml.cs
+++ b/Mlaumcherb.Client.Avalonia/зримое/MainWindow.axaml.cs
@@ -32,13 +32,13 @@ public partial class MainWindow : Window
         set => SetValue(MemoryLimitProperty, value);
     }
     
-    public static readonly StyledProperty<bool> CheckGameFilesProperty =
-        AvaloniaProperty.Register<MainWindow, bool>(nameof(CheckGameFiles),
+    public static readonly StyledProperty<bool> UpdateGameFilesProperty =
+        AvaloniaProperty.Register<MainWindow, bool>(nameof(UpdateGameFiles),
             defaultBindingMode: BindingMode.TwoWay, defaultValue: false);
-    public bool CheckGameFiles
+    public bool UpdateGameFiles
     {
-        get => GetValue(CheckGameFilesProperty);
-        set => SetValue(CheckGameFilesProperty, value);
+        get => GetValue(UpdateGameFilesProperty);
+        set => SetValue(UpdateGameFilesProperty, value);
     }
     
     
@@ -65,7 +65,7 @@ public partial class MainWindow : Window
         InitializeComponent();
     }
     
-    protected override async void OnLoaded(RoutedEventArgs e)
+    protected override void OnLoaded(RoutedEventArgs e)
     {
         try
         {
@@ -75,28 +75,14 @@ public partial class MainWindow : Window
             MemoryLimit = LauncherApp.Config.max_memory;
             EnableJavaDownload = LauncherApp.Config.download_java;
             RedirectGameOutput = LauncherApp.Config.redirect_game_output;
-
-            InstalledVersionComboBox.SelectedIndex = 0;
-            InstalledVersionComboBox.IsEnabled = false;
-            var versions = await GameVersion.GetAllVersionsAsync();
-            Dispatcher.UIThread.Invoke(() =>
+            
+            foreach (var vc in LauncherApp.Config.version_catalogs)
             {
-                foreach (var p in versions)
-                {
-                    InstalledVersionComboBox.Items.Add(new VersionItemView(p));
-                    // select last played version
-                    if (LauncherApp.Config.last_launched_version != null &&
-                        p.Name == LauncherApp.Config.last_launched_version)
-                        InstalledVersionComboBox.SelectedIndex = InstalledVersionComboBox.Items.Count - 1;
-                }
-                InstalledVersionComboBox.IsEnabled = true;
-
-                foreach (var vc in LauncherApp.Config.version_catalogs)
-                {
-                    VersionCatalogComboBox.Items.Add(vc);
-                }
-                VersionCatalogComboBox.SelectedIndex = 0;
-            });
+                RemoteVersionCatalogComboBox.Items.Add(vc);
+            }
+            RemoteVersionCatalogComboBox.SelectedIndex = 0;
+            
+            UpdateInstalledVersionsCatalogView(LauncherApp.Config.last_launched_version);
         }
         catch (Exception ex)
         {
@@ -104,6 +90,39 @@ public partial class MainWindow : Window
         }
     }
 
+    private void UpdateInstalledVersionsCatalogView(string? selectVersion)
+    {
+        LauncherApp.InstalledVersionCatalog.CheckInstalledVersions();
+        InstalledVersionCatalogComboBox.IsEnabled = false;
+        InstalledVersionCatalogComboBox.Items.Clear();
+        foreach (var p in LauncherApp.InstalledVersionCatalog.versions)
+        {
+            InstalledVersionCatalogComboBox.Items.Add(new InstalledGameVersionItemView(p.Value));
+        }
+        
+        InstalledVersionCatalogComboBox.SelectedItem = null;
+        if(selectVersion is not null 
+           && LauncherApp.InstalledVersionCatalog.versions.TryGetValue(selectVersion, out var props))
+        {
+            foreach (InstalledGameVersionItemView? view in InstalledVersionCatalogComboBox.Items)
+            {
+                if (view?.Props.Id == props.Id)
+                {
+                    InstalledVersionCatalogComboBox.SelectedItem = view;
+                    break;
+                }
+            }
+        }
+        
+        InstalledVersionCatalogComboBox.IsEnabled = true;
+    }
+
+    private void RescanInstalledVersionsButton_OnClick(object? sender, RoutedEventArgs e)
+    {
+        var selectedVersionView = InstalledVersionCatalogComboBox.SelectedItem as InstalledGameVersionItemView;
+        UpdateInstalledVersionsCatalogView(selectedVersionView?.Props.Id);
+    }
+    
     private void GuiLogMessage(LauncherLogger.LogMessage msg)
     {
         if (msg.severity == LogSeverity.Debug) return;
@@ -121,21 +140,19 @@ public partial class MainWindow : Window
     {
         try
         {
-            Dispatcher.UIThread.Invoke(() => LaunchButton.IsEnabled = false);
+            if (InstalledVersionCatalogComboBox.SelectedItem is not InstalledGameVersionItemView selectedVersionView) 
+                return;
             
-            var selectedVersionView = (VersionItemView?)InstalledVersionComboBox.SelectedItem;
-            var selectedVersion = selectedVersionView?.Props;
-            LauncherApp.Config.last_launched_version = selectedVersion?.Name;
+            Dispatcher.UIThread.Invoke(() => LaunchButton.IsEnabled = false);
+            LauncherApp.Config.last_launched_version = selectedVersionView.Props.Id;
             LauncherApp.Config.player_name = PlayerName;
             LauncherApp.Config.max_memory = MemoryLimit;
             LauncherApp.Config.download_java = EnableJavaDownload;
             LauncherApp.Config.redirect_game_output = RedirectGameOutput;
             LauncherApp.Config.SaveToFile();
-            if (selectedVersion == null) 
-                return;
             
-            var v = await GameVersion.CreateFromPropsAsync(selectedVersion, CheckGameFiles);
-            await v.UpdateFiles(CheckGameFiles, nt =>
+            var v = await selectedVersionView.Props.LoadDescriptor(UpdateGameFiles);
+            await v.Download(UpdateGameFiles, nt =>
                 {
                     Dispatcher.UIThread.Invoke(() =>
                     {
@@ -146,7 +163,7 @@ public partial class MainWindow : Window
             );
             Dispatcher.UIThread.Invoke(() =>
             {
-                CheckGameFiles = false;
+                UpdateGameFiles = false;
             });
             await v.Launch();
         }
@@ -156,10 +173,7 @@ public partial class MainWindow : Window
         }
         finally
         {
-            Dispatcher.UIThread.Invoke(() =>
-            {
-                LaunchButton.IsEnabled = true;
-            });
+            Dispatcher.UIThread.Invoke(() => LaunchButton.IsEnabled = true);
         }
     }
 
@@ -217,72 +231,33 @@ public partial class MainWindow : Window
         }
         DownloadsPanel.Children.Clear();
     }
-
-    private async void DeleteVersionButton_OnClick(object? sender, RoutedEventArgs e)
-    {
-        try
-        {
-            VersionItemView? sel = InstalledVersionComboBox.SelectedItem as VersionItemView;
-            if(sel is null)
-                return;
-        
-            var box = MessageBoxManager.GetMessageBoxCustom(new MessageBoxCustomParams
-                {
-                    ButtonDefinitions = new List<ButtonDefinition> { new() { Name = "Да" }, new() { Name = "Нет" } },
-                    ContentTitle = $"Удаление версии {sel.Props.Name}",
-                    ContentMessage = $"Вы уверены, что хотите удалить версию {sel.Props.Name}? Все файлы, включая сохранения, будут удалены!",
-                    Icon = MsBox.Avalonia.Enums.Icon.Question,
-                    WindowStartupLocation = WindowStartupLocation.CenterOwner,
-                    SizeToContent = SizeToContent.WidthAndHeight,
-                    ShowInCenter = true,
-                    Topmost = true
-                }
-            );
-            var result = await box.ShowAsync().ConfigureAwait(false);
-            if (result != "Да") 
-                return;
-            
-            sel.Props.DeleteFiles();
-            Dispatcher.UIThread.Invoke(() =>
-            {
-                InstalledVersionComboBox.Items.Remove(sel);
-            });
-        }
-        catch (Exception ex)
-        {
-            ErrorHelper.ShowMessageBox(nameof(MainWindow), ex);
-        }
-    }
     
     private async void SearchVersionsButton_OnClick(object? sender, RoutedEventArgs e)
     {
         try 
         {
-            var catalogProps = VersionCatalogComboBox.SelectedItem as VersionCatalogProps;
-            if(catalogProps is null)
+            if(RemoteVersionCatalogComboBox.SelectedItem is not GameVersionCatalogProps catalogProps)
                 return;
 
             var catalog = await catalogProps.GetVersionCatalogAsync();
-            var searchParams = new VersionSearchParams();
-            Dispatcher.UIThread.Invoke(() =>
+            var searchParams = new VersionSearchParams
             {
-                searchParams.ReleaseTypeAllowed = ReleaseVersionTypeCheckBox.IsChecked ?? false;
-                searchParams.SnapshotTypeAllowed = SnapshotVersionTypeCheckBox.IsChecked ?? false;
-                searchParams.OldTypeAllowed = OldVersionTypeCheckBox.IsChecked ?? false;
-                searchParams.OtherTypeAllowed = OtherVersionTypeAlphaCheckBox.IsChecked ?? false;
-            });
+                ReleaseTypeAllowed = ReleaseVersionTypeCheckBox.IsChecked ?? false,
+                SnapshotTypeAllowed = SnapshotVersionTypeCheckBox.IsChecked ?? false,
+                OldTypeAllowed = OldVersionTypeCheckBox.IsChecked ?? false,
+                OtherTypeAllowed = OtherVersionTypeAlphaCheckBox.IsChecked ?? false
+            };
             var versions = catalog.GetDownloadableVersions(searchParams);
             
             Dispatcher.UIThread.Invoke(() =>
             {
-                VersionCatalogItemsComboBox.IsEnabled = false;
-                VersionCatalogItemsComboBox.Items.Clear();
+                RemoteVersionCatalogItemsComboBox.IsEnabled = false;
+                RemoteVersionCatalogItemsComboBox.Items.Clear();
                 foreach (var p in versions)
                 {
-                    VersionCatalogItemsComboBox.Items.Add(new VersionItemView(p));
+                    RemoteVersionCatalogItemsComboBox.Items.Add(new RemoteGameVersionItemView(p));
                 }
-                VersionCatalogItemsComboBox.SelectedIndex = 0;
-                VersionCatalogItemsComboBox.IsEnabled = true;
+                RemoteVersionCatalogItemsComboBox.IsEnabled = true;
                 AddVersionButton.IsEnabled = versions.Count > 0;
             });
         }
@@ -296,12 +271,57 @@ public partial class MainWindow : Window
     {
         try
         {
-            var selectedVersionView = VersionCatalogItemsComboBox.SelectedItem as VersionItemView;
-            if(selectedVersionView is null)
+            if(RemoteVersionCatalogComboBox.SelectedItem is not GameVersionCatalogProps catalogProps)
                 return;
             
-            InstalledVersionComboBox.Items.Insert(0, new VersionItemView(selectedVersionView.Props));
-            InstalledVersionComboBox.SelectedIndex = 0;
+            if(RemoteVersionCatalogItemsComboBox.SelectedItem is not RemoteGameVersionItemView sel)
+                return;
+            
+            var installedProps = new InstalledGameVersionProps(sel.Props.id, catalogProps, sel.Props);
+            if (!LauncherApp.InstalledVersionCatalog.versions.TryAdd(sel.Props.id, installedProps))
+                throw new Exception("Версия уже была добавлена");
+            LauncherApp.InstalledVersionCatalog.Save();
+            
+            var propsView = new InstalledGameVersionItemView(installedProps);
+            InstalledVersionCatalogComboBox.Items.Insert(0, propsView);
+            InstalledVersionCatalogComboBox.SelectedItem = propsView;
+        }
+        catch (Exception ex)
+        {
+            ErrorHelper.ShowMessageBox(nameof(MainWindow), ex);
+        }
+    }
+
+    private async void DeleteVersionButton_OnClick(object? sender, RoutedEventArgs e)
+    {
+        try
+        {
+            if(InstalledVersionCatalogComboBox.SelectedItem is not InstalledGameVersionItemView sel)
+                return;
+        
+            var box = MessageBoxManager.GetMessageBoxCustom(new MessageBoxCustomParams
+                {
+                    ButtonDefinitions = new List<ButtonDefinition> { new() { Name = "Да" }, new() { Name = "Нет" } },
+                    ContentTitle = $"Удаление версии {sel.Props.Id}",
+                    ContentMessage = $"Вы уверены, что хотите удалить версию {sel.Props.Id}? Все файлы, включая сохранения, будут удалены!",
+                    Icon = MsBox.Avalonia.Enums.Icon.Question,
+                    WindowStartupLocation = WindowStartupLocation.CenterOwner,
+                    SizeToContent = SizeToContent.WidthAndHeight,
+                    ShowInCenter = true,
+                    Topmost = true
+                }
+            );
+            var result = await box.ShowAsync().ConfigureAwait(false);
+            if (result != "Да") 
+                return;
+            
+            sel.Props.Delete();
+            Dispatcher.UIThread.Invoke(() =>
+            {
+                InstalledVersionCatalogComboBox.Items.Remove(sel);
+                LauncherApp.InstalledVersionCatalog.versions.Remove(sel.Props.Id);
+                LauncherApp.InstalledVersionCatalog.Save();
+            });
         }
         catch (Exception ex)
         {
diff --git a/Mlaumcherb.Client.Avalonia/зримое/VersionItemView.axaml.cs b/Mlaumcherb.Client.Avalonia/зримое/VersionItemView.axaml.cs
deleted file mode 100644
index 3f30014..0000000
--- a/Mlaumcherb.Client.Avalonia/зримое/VersionItemView.axaml.cs
+++ /dev/null
@@ -1,34 +0,0 @@
-using Avalonia.Controls;
-using Avalonia.Media;
-using Avalonia.Threading;
-using Mlaumcherb.Client.Avalonia.классы;
-
-namespace Mlaumcherb.Client.Avalonia.зримое;
-
-public partial class VersionItemView : ListBoxItem
-{
-    public GameVersionProps Props { get; }
-    private SolidColorBrush _avaliableColor = new(Color.FromRgb(30, 130, 40));
-    private SolidColorBrush _unavaliableColor = new(Color.FromRgb(170, 70, 70));
-
-    public VersionItemView()
-    {
-        throw new Exception();
-    }
-    
-    public VersionItemView(GameVersionProps props)
-    {
-        Props = props;
-        InitializeComponent();
-        text.Text = props.Name;
-        props.StatusChanged += UpdateBackground;
-        UpdateBackground(props.IsDownloaded);
-    }
-
-    private void UpdateBackground(bool isDownloaded)
-    {
-        Dispatcher.UIThread.Invoke(() => 
-            Background = isDownloaded ? _avaliableColor : _unavaliableColor
-        );
-    }
-}
\ No newline at end of file
diff --git a/Mlaumcherb.Client.Avalonia/классы/Буржуазия/GameVersionCatalog.cs b/Mlaumcherb.Client.Avalonia/классы/Буржуазия/GameVersionCatalog.cs
index 6a221db..e754ec4 100644
--- a/Mlaumcherb.Client.Avalonia/классы/Буржуазия/GameVersionCatalog.cs
+++ b/Mlaumcherb.Client.Avalonia/классы/Буржуазия/GameVersionCatalog.cs
@@ -9,13 +9,13 @@ public record VersionSearchParams
 }
 
 public class GameVersionCatalog
-{
-    [JsonRequired] public List<RemoteVersionDescriptorProps> versions { get; set; } = null!;
+{ 
+    [JsonRequired] public List<RemoteVersionDescriptorProps> versions { get; set; } = new();
     
     /// <returns>empty list if couldn't find any remote versions</returns>
-    public List<GameVersionProps> GetDownloadableVersions(VersionSearchParams p)
+    public List<RemoteVersionDescriptorProps> GetDownloadableVersions(VersionSearchParams p)
     {
-        var _versionPropsList = new List<GameVersionProps>();
+        var _versionPropsList = new List<RemoteVersionDescriptorProps>();
         foreach (var r in versions)
         {
             bool match = r.type switch
@@ -26,7 +26,7 @@ public class GameVersionCatalog
                 _ => p.OtherTypeAllowed
             };
             if(match)
-                _versionPropsList.Add(new GameVersionProps(r));
+                _versionPropsList.Add(r);
         }
         return _versionPropsList;
     }
diff --git a/Mlaumcherb.Client.Avalonia/классы/Буржуазия/GameVersionDescriptor.cs b/Mlaumcherb.Client.Avalonia/классы/Буржуазия/GameVersionDescriptor.cs
index 90fde89..3d67d3f 100644
--- a/Mlaumcherb.Client.Avalonia/классы/Буржуазия/GameVersionDescriptor.cs
+++ b/Mlaumcherb.Client.Avalonia/классы/Буржуазия/GameVersionDescriptor.cs
@@ -10,7 +10,7 @@ public class GameVersionDescriptor
     [JsonRequired] public DateTime releaseTime { get; set; }
     [JsonRequired] public string type { get; set; } = "";
     [JsonRequired] public string mainClass { get; set; } = "";
-    [JsonRequired] public List<Library> libraries { get; set; } = null!;
+    [JsonRequired] public List<Library> libraries { get; set; } = new();
     [JsonRequired] public AssetIndexProperties assetIndex { get; set; } = null!;
     [JsonRequired] public string assets { get; set; } = "";
     public Downloads? downloads { get; set; } = null;
diff --git a/Mlaumcherb.Client.Avalonia/классы/Буржуазия/JavaVersionCatalog.cs b/Mlaumcherb.Client.Avalonia/классы/Буржуазия/JavaVersionCatalog.cs
index 38fde24..86318a5 100644
--- a/Mlaumcherb.Client.Avalonia/классы/Буржуазия/JavaVersionCatalog.cs
+++ b/Mlaumcherb.Client.Avalonia/классы/Буржуазия/JavaVersionCatalog.cs
@@ -67,7 +67,7 @@ public class JavaVersionProps
 
 public class JavaDistributiveManifest
 {
-    [JsonRequired] public Dictionary<string, JavaDistributiveElementProps> files { get; set; } = null!;
+    [JsonRequired] public Dictionary<string, JavaDistributiveElementProps> files { get; set; } = new();
 }
 
 public class JavaDistributiveElementProps
diff --git a/Mlaumcherb.Client.Avalonia/классы/Пролетариат/VersionCatalogProps.cs b/Mlaumcherb.Client.Avalonia/классы/Пролетариат/GameVersionCatalogProps.cs
similarity index 89%
rename from Mlaumcherb.Client.Avalonia/классы/Пролетариат/VersionCatalogProps.cs
rename to Mlaumcherb.Client.Avalonia/классы/Пролетариат/GameVersionCatalogProps.cs
index d8a8c40..d93b000 100644
--- a/Mlaumcherb.Client.Avalonia/классы/Пролетариат/VersionCatalogProps.cs
+++ b/Mlaumcherb.Client.Avalonia/классы/Пролетариат/GameVersionCatalogProps.cs
@@ -3,14 +3,13 @@
 namespace Mlaumcherb.Client.Avalonia.классы;
 
 
-public class VersionCatalogProps
+public class GameVersionCatalogProps
 {
     [JsonRequired] public required string name { get; init; }
     [JsonRequired] public required string url { get; init; }
         
     public override string ToString() => name;
     
-    
     public async Task<GameVersionCatalog> GetVersionCatalogAsync()
     {
         return await NetworkHelper.DownloadStringAndDeserialize<GameVersionCatalog>(url);
diff --git a/Mlaumcherb.Client.Avalonia/классы/Пролетариат/GameVersionProps.cs b/Mlaumcherb.Client.Avalonia/классы/Пролетариат/GameVersionProps.cs
deleted file mode 100644
index 0c7cbb3..0000000
--- a/Mlaumcherb.Client.Avalonia/классы/Пролетариат/GameVersionProps.cs
+++ /dev/null
@@ -1,83 +0,0 @@
-using Mlaumcherb.Client.Avalonia.зримое;
-using Mlaumcherb.Client.Avalonia.холопы;
-
-namespace Mlaumcherb.Client.Avalonia.классы;
-
-public class GameVersionProps : IComparable<GameVersionProps>, IEquatable<GameVersionProps>
-{
-    public string Name { get; }
-    public IOPath LocalDescriptorPath { get; }
-    public RemoteVersionDescriptorProps? RemoteProps { get; }
-    private bool _isDownloaded;
-    public bool IsDownloaded
-    {
-        get => _isDownloaded;
-        set
-        {
-            if(_isDownloaded != value)
-            {
-                _isDownloaded = value;
-                StatusChanged?.Invoke(value);
-            }
-        }
-    }
-    public event Action<bool>? StatusChanged;
-
-    private GameVersionProps(string name, RemoteVersionDescriptorProps? remoteProps)
-    {
-        
-        Name = name;
-        RemoteProps = remoteProps;
-        LocalDescriptorPath = PathHelper.GetVersionDescriptorPath(name);
-        IsDownloaded = File.Exists(PathHelper.GetVersionJarFilePath(name));
-    }
-    
-    public GameVersionProps(string name) 
-        : this(name, null)
-    { }
-    
-    public GameVersionProps(RemoteVersionDescriptorProps remoteProps)
-        : this(remoteProps.id, remoteProps)
-    { }
-
-    public void DeleteFiles()
-    {
-        IsDownloaded = false;
-        LauncherApp.Logger.LogInfo(Name, "Deleting files...");
-        var verdir = PathHelper.GetVersionDir(Name);
-        if(Directory.Exists(verdir))
-            Directory.Delete(verdir);
-        LauncherApp.Logger.LogInfo(Name, "Files deleted");
-    }
-    
-    public override string ToString() => Name;
-
-    public override int GetHashCode() => Name.GetHashCode();
-
-    public int CompareTo(GameVersionProps? other)
-    {
-        if (ReferenceEquals(this, other)) return 0;
-        if (other is null) return 1;
-        
-        if (Version.TryParse(Name, out var version1) && Version.TryParse(other.Name, out var version2))
-        {
-            return version1.CompareTo(version2);
-        }
-        
-        return String.Compare(Name, other.Name, StringComparison.InvariantCulture);
-    }
-
-    public bool Equals(GameVersionProps? other)
-    {
-        if (other is null) return false;
-        if (ReferenceEquals(this, other)) return true;
-        return Name == other.Name;
-    }
-
-    public override bool Equals(object? obj)
-    {
-        if (obj is GameVersionProps other) return Equals(other);
-        if (ReferenceEquals(this, obj)) return true;
-        return false;
-    }
-}
diff --git a/Mlaumcherb.Client.Avalonia/классы/Пролетариат/InstalledGameVersionProps.cs b/Mlaumcherb.Client.Avalonia/классы/Пролетариат/InstalledGameVersionProps.cs
new file mode 100644
index 0000000..b337d4a
--- /dev/null
+++ b/Mlaumcherb.Client.Avalonia/классы/Пролетариат/InstalledGameVersionProps.cs
@@ -0,0 +1,134 @@
+using Mlaumcherb.Client.Avalonia.зримое;
+using Mlaumcherb.Client.Avalonia.сеть;
+using Mlaumcherb.Client.Avalonia.холопы;
+using Newtonsoft.Json.Linq;
+
+namespace Mlaumcherb.Client.Avalonia.классы;
+
+public class InstalledGameVersionProps : IComparable<InstalledGameVersionProps>, IEquatable<InstalledGameVersionProps>
+{
+    [JsonRequired] public string Id { get; }
+    public GameVersionCatalogProps? CatalogProps { get; set; }
+
+    public RemoteVersionDescriptorProps? DescriptorProps { get; set; }
+    
+
+    private bool _isInstalled;
+    [JsonIgnore]
+    public bool IsInstalled
+    {
+        get => _isInstalled;
+        set
+        {
+            _isInstalled = value;
+            StatusChanged?.Invoke(value);
+        }
+    }
+
+    [JsonIgnore] public IOPath DescriptorPath { get; }
+    
+    public event Action<bool>? StatusChanged;
+
+    public InstalledGameVersionProps(string id, GameVersionCatalogProps? catalogProps, RemoteVersionDescriptorProps? descriptorProps)
+    {
+        this.Id = id;
+        this.CatalogProps = catalogProps;
+        this.DescriptorProps = descriptorProps;
+        DescriptorPath = PathHelper.GetVersionDescriptorPath(id);
+        IsInstalled = File.Exists(PathHelper.GetVersionJarFilePath(id));
+    }
+
+    public async Task<GameVersion> LoadDescriptor(bool checkForUpdates)
+    {
+        // check if DescriptorProps had been changed on on remote version catalog server
+        if (checkForUpdates && CatalogProps is not null && DescriptorProps is not null)
+        {
+            var remoteCatalog = await NetworkHelper.DownloadStringAndDeserialize<GameVersionCatalog>(CatalogProps.url);
+
+            DescriptorProps = remoteCatalog.versions.Find(remoteProps => remoteProps.id == Id);
+            if(DescriptorProps is null)
+                LauncherApp.Logger.LogWarn(nameof(InstalledGameVersionProps), 
+                    $"Game version '{Id}' was deleted from remote catalog '{CatalogProps.name}'."
+                    + "It is kept locally, but can't be updated anymore.");
+        }
+        
+        // Descriptor is downloaded here
+        if (HashHelper.CheckFileSHA1(DescriptorPath, DescriptorProps?.sha1, checkForUpdates))
+        {
+            if (DescriptorProps is null)
+                throw new NullReferenceException(
+                    $"can't download game version descriptor '{Id}', because RemoteDescriptor is null");
+            // download descriptor
+            await NetworkHelper.DownloadFile(DescriptorProps.url, DescriptorPath);
+        }
+
+        string descriptorText = File.ReadAllText(DescriptorPath);
+        JObject descriptorRaw =  JObject.Parse(descriptorText);
+        
+        // Descriptors can inherit from other descriptors.
+        // For example, 1.12.2-forge-14.23.5.2860 inherits from 1.12.2
+        if (descriptorRaw.TryGetValue("inheritsFrom", out var v))
+        {
+            string parentDescriptorId = v.Value<string>() 
+                                        ?? throw new Exception("inheritsFrom is null");
+            LauncherApp.Logger.LogInfo(Id, $"merging descriptor '{parentDescriptorId}' with '{Id}'");
+            IOPath parentDescriptorPath = PathHelper.GetVersionDescriptorPath(parentDescriptorId);
+            if (!File.Exists(parentDescriptorPath))
+                throw new Exception($"Версия '{Id} требует установить версию '{parentDescriptorId}'");
+            string parentDescriptorText = File.ReadAllText(parentDescriptorPath);
+            JObject parentDescriptorRaw = JObject.Parse(parentDescriptorText);
+            parentDescriptorRaw.Merge(descriptorRaw,
+                new JsonMergeSettings { MergeArrayHandling = MergeArrayHandling.Concat });
+            descriptorRaw = parentDescriptorRaw;
+            // removing dependency
+            descriptorRaw.Remove("inheritsFrom");
+            File.WriteAllText(DescriptorPath, descriptorRaw.ToString());
+        }
+
+        var descriptor = descriptorRaw.ToObject<GameVersionDescriptor>()
+                      ?? throw new Exception($"can't parse descriptor file '{DescriptorPath}'");
+        
+        return new GameVersion(this, descriptor);
+    }
+    
+    public void Delete()
+    {
+        if(!IsInstalled)
+            return;
+        
+        LauncherApp.Logger.LogInfo(Id, "Deleting files...");
+        var verdir = PathHelper.GetVersionDir(Id);
+        if(Directory.Exists(verdir))
+            Directory.Delete(verdir);
+        LauncherApp.Logger.LogInfo(Id, "Files deleted");
+        IsInstalled = false;
+    }
+    
+    public override string ToString() => Id;
+
+    public override int GetHashCode() => Id.GetHashCode();
+
+    public int CompareTo(InstalledGameVersionProps? other)
+    {
+        if (ReferenceEquals(this, other)) 
+            return 0;
+        if (other is null) 
+            return 1;
+        
+        return String.Compare(Id, other.Id, StringComparison.InvariantCulture);
+    }
+
+    public bool Equals(InstalledGameVersionProps? other)
+    {
+        if (other is null) return false;
+        if (ReferenceEquals(this, other)) return true;
+        return Id == other.Id;
+    }
+
+    public override bool Equals(object? obj)
+    {
+        if (obj is InstalledGameVersionProps other) return Equals(other);
+        if (ReferenceEquals(this, obj)) return true;
+        return false;
+    }
+}
diff --git a/Mlaumcherb.Client.Avalonia/классы/Пролетариат/InstalledVersionCatalog.cs b/Mlaumcherb.Client.Avalonia/классы/Пролетариат/InstalledVersionCatalog.cs
new file mode 100644
index 0000000..f6ba541
--- /dev/null
+++ b/Mlaumcherb.Client.Avalonia/классы/Пролетариат/InstalledVersionCatalog.cs
@@ -0,0 +1,77 @@
+using System.Linq;
+using Mlaumcherb.Client.Avalonia.зримое;
+using Mlaumcherb.Client.Avalonia.холопы;
+
+namespace Mlaumcherb.Client.Avalonia.классы;
+
+public class InstalledVersionCatalog
+{
+    /// version_id, props
+    [JsonRequired] public Dictionary<string, InstalledGameVersionProps> versions { get; set; } = new();
+
+    private IComparer<InstalledGameVersionProps> reverseComparer = new ReverseComparer<InstalledGameVersionProps>();
+    
+    public static InstalledVersionCatalog Load()
+    {
+        InstalledVersionCatalog catalog;
+        var installedCatalogPath = PathHelper.GetInstalledVersionCatalogPath();
+        if (!File.Exists(installedCatalogPath))
+        {
+            LauncherApp.Logger.LogDebug(nameof(InstalledVersionCatalog), "creating new catalog");
+            catalog = new InstalledVersionCatalog();
+        }
+        else
+        {
+            LauncherApp.Logger.LogDebug(nameof(InstalledVersionCatalog), "loading catalog from file");
+            catalog = JsonConvert.DeserializeObject<InstalledVersionCatalog>(
+                          File.ReadAllText(installedCatalogPath))
+                      ?? throw new NullReferenceException($"can't deserialize {installedCatalogPath}");
+        }
+
+        catalog.CheckInstalledVersions();
+        catalog.Save();
+        return catalog;
+    }
+
+    public void Save()
+    {
+        var installedCatalogPath = PathHelper.GetInstalledVersionCatalogPath();
+        LauncherApp.Logger.LogDebug(nameof(InstalledVersionCatalog), "saving catalog to file");
+        var text = JsonConvert.SerializeObject(this, Formatting.Indented);
+        File.WriteAllText(installedCatalogPath, text);
+        LauncherApp.Logger.LogDebug(nameof(InstalledVersionCatalog), "catalog has been saved");
+    }
+
+    /// <summary>
+    /// Check if any versions were installed or deleted manually.
+    /// </summary>
+    public void CheckInstalledVersions()
+    {
+        var versionsUpdated = new List<InstalledGameVersionProps>();
+        Directory.Create(PathHelper.GetVersionsDir());
+        foreach (var subdir in Directory.GetDirectories(PathHelper.GetVersionsDir()))
+        {
+            string id = subdir.LastName().ToString();
+            if (!File.Exists(PathHelper.GetVersionDescriptorPath(id)))
+                throw new Exception(
+                    $"Can't find version descriptor file in directory '{subdir}'. Rename it as directory name.");
+            
+            if (versions.TryGetValue(id, out var foundProps))
+            {
+                versionsUpdated.Add(foundProps);
+            }
+            else
+            {
+                versionsUpdated.Add(new InstalledGameVersionProps(id, null, null));
+            }
+        }
+
+        // reverse sort
+        versionsUpdated.Sort(reverseComparer);
+        // create dictionary from list
+        versions = new Dictionary<string, InstalledGameVersionProps>(
+            versionsUpdated.Select(props =>
+                new KeyValuePair<string, InstalledGameVersionProps>(props.Id, props)
+            ));
+    }
+}
\ No newline at end of file
diff --git a/Mlaumcherb.Client.Avalonia/классы/Пролетариат/FilesManifest.cs b/Mlaumcherb.Client.Avalonia/классы/Пролетариат/ModpackFilesManifest.cs
similarity index 90%
rename from Mlaumcherb.Client.Avalonia/классы/Пролетариат/FilesManifest.cs
rename to Mlaumcherb.Client.Avalonia/классы/Пролетариат/ModpackFilesManifest.cs
index cffeddb..c3f8e98 100644
--- a/Mlaumcherb.Client.Avalonia/классы/Пролетариат/FilesManifest.cs
+++ b/Mlaumcherb.Client.Avalonia/классы/Пролетариат/ModpackFilesManifest.cs
@@ -6,7 +6,7 @@ public class ModpackFilesManifest
 {
     public class FileProps
     {
-        [JsonRequired] public string sha1 { get; set; }
+        [JsonRequired] public string sha1 { get; set; } = "";
         public bool allow_edit { get; set; } = false;
     }
     
diff --git a/Mlaumcherb.Client.Avalonia/классы/Пролетариат/MyModpack.cs b/Mlaumcherb.Client.Avalonia/классы/Пролетариат/MyModpack.cs
index 4ed7e54..757df62 100644
--- a/Mlaumcherb.Client.Avalonia/классы/Пролетариат/MyModpack.cs
+++ b/Mlaumcherb.Client.Avalonia/классы/Пролетариат/MyModpack.cs
@@ -11,7 +11,7 @@ public class MyModpackV1
 
     // 1
     [JsonRequired] public int format_version { get; set; }
-    [JsonRequired] public string name { get; set; }
+    [JsonRequired] public string name { get; set; } = "";
     // zip archive with all files
     [JsonRequired] public Artifact zip { get; set; } = null!;
     // ModpackFilesManifest
diff --git a/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/LibrariesDownloadTaskFactory.cs b/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/LibrariesDownloadTaskFactory.cs
index acf9e7a..c88b0ea 100644
--- a/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/LibrariesDownloadTaskFactory.cs
+++ b/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/LibrariesDownloadTaskFactory.cs
@@ -43,7 +43,7 @@ public class LibrariesDownloadTaskFactory : INetworkTaskFactory
             {
                 _libsToDownload.Add(l);
             }
-            //TODO: replace with actual native assets check
+            //TODO: replace with actual native libraries check
             else if (!nativeDirExists && l is Libraries.NativeLib)
             {
                 _libsToDownload.Add(l);
@@ -79,18 +79,15 @@ public class LibrariesDownloadTaskFactory : INetworkTaskFactory
             if (l is Libraries.NativeLib n)
             {
                 await using var zipf = File.OpenRead(n.jarFilePath);
-                //TODO: replace following code with manual extraction
-                ZipFile.ExtractToDirectory(zipf, _nativesDir.ToString(), true);
-                if (n.extractionOptions?.exclude != null)
+                using var archive = new ZipArchive(zipf);
+                foreach (var entry in archive.Entries)
                 {
-                    foreach (var excluded in n.extractionOptions.exclude)
-                    {
-                        IOPath path = Path.Concat(_nativesDir, excluded);
-                        if(Directory.Exists(path))
-                            Directory.Delete(path);
-                        if(File.Exists(path))
-                            File.Delete(path);
-                    }
+                    if (n.extractionOptions?.exclude?.Contains(entry.FullName) is true or null) 
+                        continue;
+                    
+                    var real_path = Path.Concat(_nativesDir, entry.FullName);
+                    Directory.Create(real_path.ParentDir());
+                    entry.ExtractToFile(real_path.ToString(), true);
                 }
             }
         });
diff --git a/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/ModpackDownloadTaskFactory.cs b/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/ModpackDownloadTaskFactory.cs
index 4bba49b..d52b376 100644
--- a/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/ModpackDownloadTaskFactory.cs
+++ b/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/ModpackDownloadTaskFactory.cs
@@ -81,7 +81,7 @@ public class MyModpackV1DownloadTaskFactory : INetworkTaskFactory
         if(string.IsNullOrEmpty(_modpack.zip.url))
             throw new Exception($"modpack '{_modpack.name}' doesn't have a url to download");
 
-        var _archivePath = Path.Concat("downloads/modpacks", _modpack.name + ".zip");
+        var _archivePath = Path.Concat(PathHelper.GetCacheDir(), "modpacks", _modpack.name + ".zip");
         await NetworkHelper.DownloadFile(_modpack.zip.url, _archivePath, ct, pr.AddBytesCount);
         
         await using var zipf = File.OpenRead(_archivePath);
diff --git a/Mlaumcherb.Client.Avalonia/холопы/PathHelper.cs b/Mlaumcherb.Client.Avalonia/холопы/PathHelper.cs
index 6ce73a1..3d56b8d 100644
--- a/Mlaumcherb.Client.Avalonia/холопы/PathHelper.cs
+++ b/Mlaumcherb.Client.Avalonia/холопы/PathHelper.cs
@@ -60,4 +60,9 @@ public static class PathHelper
     
     public static IOPath GetModpackManifestPath(string game_version) => 
         Path.Concat(GetVersionDir(game_version), "timerix_modpack_files.json");
+
+    public static IOPath GetCacheDir() =>
+        Path.Concat(GetRootFullPath(), "cache");
+    public static IOPath GetInstalledVersionCatalogPath() =>
+        Path.Concat(GetCacheDir(), "installed_versions.json");
 }
diff --git a/Mlaumcherb.Client.Avalonia/холопы/ReverseComparer.cs b/Mlaumcherb.Client.Avalonia/холопы/ReverseComparer.cs
new file mode 100644
index 0000000..13033e3
--- /dev/null
+++ b/Mlaumcherb.Client.Avalonia/холопы/ReverseComparer.cs
@@ -0,0 +1,12 @@
+namespace Mlaumcherb.Client.Avalonia.холопы;
+
+// compares Y with X instead of X with Y
+public class ReverseComparer<T> : IComparer<T> where T : IComparable<T>
+{
+    public int Compare(T? x, T? y)
+    {
+        if (y is null)
+            return x is null ? 0 : -1;
+        return y.CompareTo(x);
+    }
+}
\ No newline at end of file