move the level instance to a level node so that pausing the game doesn't effect the main node

godot/Main.tscn

@@ -5,7 +5,11 @@
 [ext_resource path="res://monitor/Monitor.tscn" type="PackedScene" id=3]
 
 [node name="Main" type="Node"]
+pause_mode = 2
 script = ExtResource( 1 )
 level = ExtResource( 2 )
 
+[node name="Level" type="Node" parent="."]
+pause_mode = 1
+
 [node name="Monitor" parent="." instance=ExtResource( 3 )]

src/Main.cpp

@@ -52,7 +52,7 @@ void Main::_ready()
 
     if (level != NULL)
     {
-        add_child(level->instance());
+        get_node("Level")->add_child(level->instance());
     }
 }