Solar 2 is one of Steam's best-kept secrets. It's equal parts space physics simulator and arcade game.
I find it very relaxing and entertaining to zip around space, gobbling up asteroids into a giant star-katamari and evolving my planets.
It's not a perfect game. I wish that there was a better way to battle star-vs-star with the AI. The best strategy I've found for stealing planets is to knock them out of orbit with a shielded planet, then chase them down. This works, but it's very damaging to your suns and planets, and tends not to be worth the effort. The best strategy for growth is roaming about the galaxy looking for free planets and asteroids to grow your system.
No matter. Solar 2 is not really designed for long-term play. I find it works best to pop in for a while and just knock around a bit. See if you have the patience to develop an 8-star system, for instance.
The missions offer a nice break to the gameplay, but some are easy and some are very frustrating. It's a mixed bag.
A Multiplayer mode would have been welcome, too. Still, I find little to complain about in Solar 2. It's not perfect, but it is a light and fun sandbox game, which lets you decide how you want to have fun. Try the Demo.