In fact it is possible to detect UFOs, but the chances are rather modest - in the beginning you must rely on random reports and incoming calls, which is represented by the HQ building. So I can't say if it's XCF or not.
You can attach a save like Meridian said, but it is evident at first glance if it's vanilla or XCF - there are different buildings, different craft (you start with a car), agents wear suits and there are only 2, etc.