Kerbal Space Program has been floating through the inky black of game development for years now, edging closer towards the ultimate goal of being a structured space program management sim. It's now in orbit above that target, having moved from alpha to beta and added new features like base building, refined features like ship construction, and a lot more. There's a trailer introducing the changes below.
As explained in the developer blog post on the subject, the beta extends functionality first touched upon in the last big update back in October, when bases were first made destructible should you accidentally crash into them. Now you can construct those bases from scratch, placing buildings and leveling them by completing contracts - which themselves have been expanded with the adoption of the Small Print mod into the core game, which adds new activities for budding space engineers.
It's exciting that you can now also level your kerbals and specialise them in pilot skills or science or repair abilities, but it's the revisions to the ship builder that may prove most significant. Connecting ship parts and constructing absurd rockets has always been a little fiddlier than desired, and given how much of your time is spent experimenting with craft designs no matter what mode you're playing, refining that process is a big deal.