What does it mean: “not really”?
You are running it or not. So what is your OS?
Suggestion – please state your setup in your Signature (OS, Service Pack; security with/without real-time; etc. That will be much appreciated When & If you are making any request(s) and will eliminate unneeded spare questions
Then,
There is no such thing as MS “Windows not made by Microsoft”
Therefore it is not “made up version” by any means.
The site and the Software you are pointing out is widely used and there are different (free or paid vendors) Software like that. The aim is just changing an appearance/interface of any given OS …and so on… but not any core features of OS you are currently running
I hope I know that you know ;), so why is you question?
In addition you can indeed run Windows 8 (whether it’s beta or final release) and still use such Software, say in order to make it look like Mac
Sure that’s just a "skinamization; Vistamization; Win7/8-mization; Mac-mization
I was just pointing out some incorrect wordings by OP (Eddie) … no offence