So what is it? It's a minecraft-esqe space sim! Following the tutorial you'll learn the basics of block placements to build a spaceship! It's as simple as adding a ship core, power, and thrusters and voila you have a (semi) functioning vessel. Once you have the basics down, this is where the hours get whittled away. I began with a simple mining vessel... which got expanded and expanded until I had 9 missile bays and 6 anti-matter cannons. It's even possible to build a ship interior allowing you to float or walk around (with a gravity generator), meaning you can have your engineering, shield generator and bridge levels all separate and live whatever science fiction reality you so wish. In fact your ship can easily be torn apart by pirate attacks, and so protecting your vital systems with a protective outer hull is an absolute necessity.
Ship movement is simple and easy, but when gravity comes into play then it gets a bit more complex. I learnt this the hard way as when entering a planet atmosphere I suddenly realised that my front-heavy ship was beginning to fall quite drastically into the ground. Lots of button mashing later I managed to break out into space with Scotty's voice ringing in my head: something 'not-enough-power' related. More experimentation into the physics of this game and how the physical build of the ship in relation to power etc is definitely necessary.
This is a sandbox game and so don't feel as though you have to stick to the rules! Building a forest on top of your ship is possible, as is placing most other blocks (I haven't tried them all)! What this does to your weight and manoeuvrability is another question to be answered but experimentation is encouraged. The website has a library of user-submitted ships which may be worth looking at for inspiration.
I won't say much else other than I definitely need to try this on a multiplayer server. Sometimes it's nice to build alone, but it's also nice to blow up your mates...
Please check it out: http://star-made.org
Enjoy! - oP