diff --git a/unity-client/Assets/Editor/BuildAllScenes.cs b/unity-client/Assets/Editor/BuildAllScenes.cs
new file mode 100644
index 0000000..a540e99
--- /dev/null
+++ b/unity-client/Assets/Editor/BuildAllScenes.cs
@@ -0,0 +1,32 @@
+#if UNITY_EDITOR
+using UnityEditor;
+using UnityEditor.SceneManagement;
+using UnityEngine;
+
+public static class BuildAllScenes
+{
+    [MenuItem("Tools/Build All Scenes")]
+    public static void BuildAll()
+    {
+        // Clear build settings first
+        EditorBuildSettings.scenes = new EditorBuildSettingsScene[0];
+
+        // Create all scenes in order (MainMenu must be index 0)
+        CreateMainMenuScene.Create();
+        CreateCollectionScene.Create();
+        CreateDeckBuilderScene.Create();
+        CreateSimulatorScene.Create();
+        CreateScannerScene.Create();
+        CreateTrainingScene.Create();
+
+        // Log the final build settings
+        Debug.Log($"[BuildAllScenes] Registered {EditorBuildSettings.scenes.Length} scenes in Build Settings:");
+        foreach (var s in EditorBuildSettings.scenes)
+            Debug.Log($"  {s.path} (enabled={s.enabled})");
+
+        // Reopen MainMenu as the active scene
+        EditorSceneManager.OpenScene("Assets/Scenes/MainMenu.unity");
+        Debug.Log("[BuildAllScenes] Done! MainMenu scene is now active.");
+    }
+}
+#endif
diff --git a/unity-client/Assets/Editor/CreateCollectionScene.cs b/unity-client/Assets/Editor/CreateCollectionScene.cs
index 08d570a..d33d46f 100644
--- a/unity-client/Assets/Editor/CreateCollectionScene.cs
+++ b/unity-client/Assets/Editor/CreateCollectionScene.cs
@@ -5,6 +5,7 @@ using UnityEditor;
 using UnityEditor.SceneManagement;
 using TMPro;
 using System.Reflection;
+using System.Linq;
 
 public static class CreateCollectionScene
 {
@@ -205,7 +206,10 @@ public static class CreateCollectionScene
             AssetDatabase.CreateFolder("Assets", "Scenes");
         string path = "Assets/Scenes/Collection.unity";
         EditorSceneManager.SaveScene(scene, path);
-        EditorBuildSettings.scenes = new EditorBuildSettingsScene[] { new EditorBuildSettingsScene(path, true) };
+        var existing = new System.Collections.Generic.List<EditorBuildSettingsScene>(EditorBuildSettings.scenes);
+        if (!existing.Any(s => s.path == path))
+            existing.Add(new EditorBuildSettingsScene(path, true));
+        EditorBuildSettings.scenes = existing.ToArray();
         Debug.Log("[CreateCollectionScene] Collection scene created and saved to " + path);
     }
 
diff --git a/unity-client/Assets/Editor/CreateDeckBuilderScene.cs b/unity-client/Assets/Editor/CreateDeckBuilderScene.cs
index 1f77210..bb4f6a7 100644
--- a/unity-client/Assets/Editor/CreateDeckBuilderScene.cs
+++ b/unity-client/Assets/Editor/CreateDeckBuilderScene.cs
@@ -5,6 +5,7 @@ using UnityEditor;
 using UnityEditor.SceneManagement;
 using TMPro;
 using System.Reflection;
+using System.Linq;
 
 public static class CreateDeckBuilderScene
 {
@@ -169,7 +170,10 @@ public static class CreateDeckBuilderScene
             AssetDatabase.CreateFolder("Assets", "Scenes");
         string path = "Assets/Scenes/DeckBuilder.unity";
         EditorSceneManager.SaveScene(scene, path);
-        EditorBuildSettings.scenes = new EditorBuildSettingsScene[] { new EditorBuildSettingsScene(path, true) };
+        var existing = new System.Collections.Generic.List<EditorBuildSettingsScene>(EditorBuildSettings.scenes);
+        if (!existing.Any(s => s.path == path))
+            existing.Add(new EditorBuildSettingsScene(path, true));
+        EditorBuildSettings.scenes = existing.ToArray();
         Debug.Log("[CreateDeckBuilderScene] DeckBuilder scene created and saved to " + path);
     }
 
diff --git a/unity-client/Assets/Editor/CreateMainMenuScene.cs b/unity-client/Assets/Editor/CreateMainMenuScene.cs
index f6b6346..ceaae90 100644
--- a/unity-client/Assets/Editor/CreateMainMenuScene.cs
+++ b/unity-client/Assets/Editor/CreateMainMenuScene.cs
@@ -6,6 +6,7 @@ using UnityEditor;
 using UnityEditor.SceneManagement;
 using TMPro;
 using System.Reflection;
+using System.Linq;
 
 public static class CreateMainMenuScene
 {
@@ -121,8 +122,10 @@ public static class CreateMainMenuScene
         // -- Save --
         string path = "Assets/Scenes/MainMenu.unity";
         EditorSceneManager.SaveScene(scene, path);
-        EditorBuildSettingsScene[] buildScenes = { new EditorBuildSettingsScene(path, true) };
-        EditorBuildSettings.scenes = buildScenes;
+        var existing = new System.Collections.Generic.List<EditorBuildSettingsScene>(EditorBuildSettings.scenes);
+        if (!existing.Any(s => s.path == path))
+            existing.Add(new EditorBuildSettingsScene(path, true));
+        EditorBuildSettings.scenes = existing.ToArray();
 
         Debug.Log("MainMenu scene created and saved to " + path);
         EditorUtility.DisplayDialog("Done", "MainMenu scene created!\n\nHit Play to test.\nMake sure your FastAPI backend is running on port 8080.", "OK");
diff --git a/unity-client/Assets/Editor/CreateScannerScene.cs b/unity-client/Assets/Editor/CreateScannerScene.cs
index aebe64a..d0277ad 100644
--- a/unity-client/Assets/Editor/CreateScannerScene.cs
+++ b/unity-client/Assets/Editor/CreateScannerScene.cs
@@ -5,6 +5,7 @@ using UnityEditor;
 using UnityEditor.SceneManagement;
 using TMPro;
 using System.Reflection;
+using System.Linq;
 
 public static class CreateScannerScene
 {
@@ -92,7 +93,10 @@ public static class CreateScannerScene
             AssetDatabase.CreateFolder("Assets", "Scenes");
         string path = "Assets/Scenes/Scanner.unity";
         EditorSceneManager.SaveScene(scene, path);
-        EditorBuildSettings.scenes = new EditorBuildSettingsScene[] { new EditorBuildSettingsScene(path, true) };
+        var existing = new System.Collections.Generic.List<EditorBuildSettingsScene>(EditorBuildSettings.scenes);
+        if (!existing.Any(s => s.path == path))
+            existing.Add(new EditorBuildSettingsScene(path, true));
+        EditorBuildSettings.scenes = existing.ToArray();
         Debug.Log("[CreateScannerScene] Scanner scene created and saved to " + path);
     }
 
diff --git a/unity-client/Assets/Editor/CreateSimulatorScene.cs b/unity-client/Assets/Editor/CreateSimulatorScene.cs
index b11a2ac..dd1469f 100644
--- a/unity-client/Assets/Editor/CreateSimulatorScene.cs
+++ b/unity-client/Assets/Editor/CreateSimulatorScene.cs
@@ -5,6 +5,7 @@ using UnityEditor;
 using UnityEditor.SceneManagement;
 using TMPro;
 using System.Reflection;
+using System.Linq;
 
 public static class CreateSimulatorScene
 {
@@ -85,7 +86,10 @@ public static class CreateSimulatorScene
             AssetDatabase.CreateFolder("Assets", "Scenes");
         string path = "Assets/Scenes/Simulator.unity";
         EditorSceneManager.SaveScene(scene, path);
-        EditorBuildSettings.scenes = new EditorBuildSettingsScene[] { new EditorBuildSettingsScene(path, true) };
+        var existing = new System.Collections.Generic.List<EditorBuildSettingsScene>(EditorBuildSettings.scenes);
+        if (!existing.Any(s => s.path == path))
+            existing.Add(new EditorBuildSettingsScene(path, true));
+        EditorBuildSettings.scenes = existing.ToArray();
         Debug.Log("[CreateSimulatorScene] Simulator scene created and saved to " + path);
     }
 
diff --git a/unity-client/Assets/Editor/CreateTrainingScene.cs b/unity-client/Assets/Editor/CreateTrainingScene.cs
index 7386045..70c08e7 100644
--- a/unity-client/Assets/Editor/CreateTrainingScene.cs
+++ b/unity-client/Assets/Editor/CreateTrainingScene.cs
@@ -5,6 +5,7 @@ using UnityEditor;
 using UnityEditor.SceneManagement;
 using TMPro;
 using System.Reflection;
+using System.Linq;
 
 public static class CreateTrainingScene
 {
@@ -170,7 +171,10 @@ public static class CreateTrainingScene
             AssetDatabase.CreateFolder("Assets", "Scenes");
         string path = "Assets/Scenes/Training.unity";
         EditorSceneManager.SaveScene(scene, path);
-        EditorBuildSettings.scenes = new EditorBuildSettingsScene[] { new EditorBuildSettingsScene(path, true) };
+        var existing = new System.Collections.Generic.List<EditorBuildSettingsScene>(EditorBuildSettings.scenes);
+        if (!existing.Any(s => s.path == path))
+            existing.Add(new EditorBuildSettingsScene(path, true));
+        EditorBuildSettings.scenes = existing.ToArray();
         UnityEngine.Debug.Log("[CreateTrainingScene] Training scene created and saved to " + path);
     }
 
diff --git a/unity-client/Assets/Scripts/UI/MainMenuController.cs b/unity-client/Assets/Scripts/UI/MainMenuController.cs
index 530b84b..37b2170 100644
--- a/unity-client/Assets/Scripts/UI/MainMenuController.cs
+++ b/unity-client/Assets/Scripts/UI/MainMenuController.cs
@@ -92,7 +92,15 @@ namespace CommanderAILab.UI
 
         private void LoadScene(string sceneName)
         {
-            if (isConnected) SceneManager.LoadScene(sceneName);
+            if (!isConnected) return;
+            try
+            {
+                SceneManager.LoadScene(sceneName);
+            }
+            catch (System.Exception e)
+            {
+                Debug.LogError($"Failed to load scene '{sceneName}': {e.Message}. Is it added to Build Settings?");
+            }
         }
     }
 }