Why should Mars rovers have all the fun? If you're tired of standing by while Curiosity rolls around up there, it's time to head out on the open exosphere and explore the universe for yourself -- digitally, of course.
A handful of excellent space simulators use real astronomical data to re-create the known universe in three dimensions. Fly through the galaxy at ludicrous speeds, map out humanity's best hope for extrasolar colonization, or mess with physics to create your own cosmic recipes.
Some of these simulations stick to our own solar system, while others push the boundaries of our cosmological projections, procedurally generating star systems far beyond our galactic neighborhood. In layman's terms: They're friggin' sweet.