Alpha 3.6 PTU (not live! Installation of the new launcher necessary) is now open to all backers. If you expect a playable game: it´s not. It´s buggy, it´s crashy, it has fps drops.
If you haven´t been into it for a while I suggest to check it out due to the new flight model, head tracking (with webcam) and beautiful new assets like R&R space stations and Planets