I tested the Solar 2 Demo just now and I must say that it is a pretty cool game. The game won the first price ($200000) in the recent Dream.Build.Play XNA competition. I love the open-ended gameplay available in the demo, and from what I've read the mission mode in the full version sound like a ton of fun too! In Solar 2 you start off as a small asteroid somewhere in space. You exert a bit of gravity and you can collide with other asteroids to grow in size. Once you reach a critical mass you turn into a small planet and you can now pull in asteroids to have them orbit you as your moons. The problem you face now is that if you collide with asteroids you will lose mass so what you want to do is to use your ability to absorb asteroids to grow in mass. While doing so life will start evolving on your planet and if you grow enough you will get an orbital shield, ground to space cannons and small spacecraft that will shoot down asteroids on collision course. The interesting thing is that you are not the only planet and soon you'll find other planets with shields, spacecrafts and ground to space cannons that want nothing else than to obliterate you.