Uhrr... I'm first round beta. :P
I honestly can't remember which beta version i have acces. I pledged the package that gave me the phisical game DRM free. And can't go check on the backer account app because it's closed momentarely.
I think i only have acces to seccond round beta.
I think the months for access are:
December: Alpha
January: First Phase Beta
February: Second Phase Beta
March onwards: Gamma before final release sometime. All backers who are entitled to the game can play from Gamma onwards.