A fantastic sequel to an amazingly original concept.
Murudai builds upon the original in not only subtle ways, such as the upgraded interface and general presentation and accessability ( including saving what you've created, probably the best addition ), but also in extensive ones.
This is most notably the missions you can choose to take, which are in turn tiered to some of the celestial objects you can manage to make of yourself, all of which are saved like in game achievements, giving you complete control of what and how you want to play. This is in turn has been built upon, with an added depth of what you as the simplest of meteorites can expand to become from your start at the big bang. Planets, stars, entire solar systems and more are all within the realms of what you can make, making this sandbox universe something to easily, and most importantly enjoyably get lost in.
That isn't to say this game is for everyone, as those wanting instant satisfaction will more than likely be put off by the general pace of the game, so in that respect I'd most definitely try the demo.
Personally though I find Solar 2 to be a vast improvement on the already original first title, and an extremely fun game to waste those times when I'm coming off of a more traditional retail game feeling unsatisfied, or simply when I feel like creating something, rather than destroying ( although destruction is very much a possibilty too! )
My only hope is that the series can expand to the endless potential it shares with the universe it mimicks. A fantastic game, and one I hope to see more sequels to in the coming years.