SpaceEngine. A 1 to 1 scale Universe simulator that features an endless number of worlds to explore, galaxies to marvel at, black holes to be afraid of. You can find yourself at home, in the Solar System, or lost in the vast sea of procedurally generated stars. Shatter the speed of light and cruise through the Universe in SpaceEngine at unimaginable speeds. Explore to your heart's content, unconstrained by time or space. Stumble upon unexplored worlds, or create new ones to your desires. The options are limitless.

website: http://spaceengine.org/
https://store.steampowered.com/app/314650/SpaceEngine/