Starbound, which can best be described as "Terraria in Space", where players explore a procedurally-generated 2D world while crafting and surviving on the landscape's resources.
The developerthat there would be three betas late in the year, and now the first beta, open to backers, is now live. The beta is not feature-set yet, but it does have multiplayer, so gamers can visit each other's planets.
It's not too late to get into the beta, as Starbound is available on Steam Early Access, and preordering for $14.99 USD will grant instant beta access.
Chucklefish also released a new trailer showing off the beta build - check it out in the video below.