Its past tech demo now, I'd call it alpha stage. They're still building features and systems and extending what is in the engine into actual gameplay.

Similar to very early pre-steam KSP, but 100x as beautiful and 100x as performant. They are consciously avoiding several of the engine pitfalls KSP was known for and are using more modern techniques.

Overall I'm really happy and excited. It's moving fast but also keeping quality fairly high.