Check maple running

Xenon/MainWindow.xaml.cs

@@ -22,8 +22,9 @@ public partial class MainWindow : Window
         public MainWindow()
         {
             InitializeComponent();
-            
+
             checkIfMapleExists();
+            checkMapleProcess();
 
             if (!String.IsNullOrEmpty(Properties.Settings.Default.username))
             {
@@ -45,13 +46,23 @@ private void Window_Loaded(object sender, RoutedEventArgs e)
 
         private void checkIfMapleExists()
         {
-            if (!Nexon.Maple.GameExists())
+            if (!Nexon.Maple.GameExists)
             {
                 MessageBox.Show("MapleStory.exe was not found. Are you sure you put Xenon into the MapleStory folder? Ensure it is NOT in the \"appdata\" folder that Nexon Launcher creates, but one step above that (by default it should be called \"maplestory\".", "Xenon", MessageBoxButton.OK, MessageBoxImage.Warning);
                 Close();
             }
         }
 
+        private void checkMapleProcess()
+        {
+            if (Nexon.Maple.GameRunning)
+            {
+                MessageBoxResult mbr = MessageBox.Show("MapleStory seems to be running on your computer. Please note that Xenon cannot be used to multi-client, and is rather only a launcher replacement! Continue anyway?", "Xenon", MessageBoxButton.YesNo, MessageBoxImage.Warning);
+                if (mbr == MessageBoxResult.No)
+                    Close();
+            }
+        }
+
         private void Button_Click(object sender, RoutedEventArgs e)
             => PerformLogin();
 

Xenon/Nexon/Maple.cs

@@ -15,9 +15,12 @@ static class Maple
     {
         public static string MaplePath = Path.Combine(Util.AppDirectory, "MapleStory.exe");
 
-        public static bool GameExists()
+        public static bool GameExists
             => File.Exists(MaplePath);
 
+        public static bool GameRunning
+            => Process.GetProcessesByName("MapleStory").Length > 0;
+
         private static string launchToken;
 
         private static Regex remoteVerRegex = new Regex(@"pub(\d+)_(\d+)_(\d+)\.manifest");