Lone_Scout: And what are the differences between this one and Universe Sandbox?
Well, for one, the SpaceEngine HD Texture packs are massive and add about 55GB to the game... you can get down and explore individual features on planets, which is not really possible in Universe Sandbox.
Otherwise, I have not played around with it that much, but it looks like the default mode is "exploration" not "sandbox", as it is in Universe Sandbox. The main intended purpose is exploration, not necessarily physics simulation, but there is a customization option (I just haven't looked much into it yet).
arrua: Does that mean it´ll take several thousand of years of gameplay to get out of the solar system?
I was able to accelerate up to thousands of light years per second, so all bet are off. Can't say I like the fact that light is still visible at that speed (it shouldn't, in theory), but what I do like is that if you travel far out enough, you get red shifted :).