Has anyone given this a go? I brought it a while ago in a Steam sale, but never got round to actually playing it. Now that I'm a poor gamedev, I'm actually dealing with my backlog :-) I was initially put off with the complexity and a rather scary looking UI, but at some point since I purchased it, there is now a really nice set of tutorial missions that helps you and walks you through some of the functionality.
It's the first time I've experienced the "oh wait, how has six hours gone by?" moment in quite a while. For those who don't know it, you are an astronaut who also happens to be a genius with a welding torch. And you need to survive by building everything from obscenely huge spaceships to even more hugely obscene spaceships (well, I'm just building little ones which are little more than a chair with some rockets - there is a lot to learn!). It's very sandboxey with a variety of different scenarios to explore. The scale of the game is also pretty dang impressive, moving from space down to a planet and being able to explore both in a lot of detail. It can be played multiplayer (which would be a lot of fun) - but I'm having plenty of fun playing it in single player.
If you've already got and haven't played it in ages give it a go, if not it is one I really do recommend purchasing when you are able :-)