Do you want to build your own virtual space craft and travel within out solar system?
Check out this game. This is what I've been goofing around with for the past 2 days.
I have a Space Station in orbit around the Earth (Kerban) and a Space Station to the Moon (Mun) is currently en route. It includes a Moon Lander. When I get it in to orbit of the Moon, I will do a space walk in to the lander, separate, and land on the Moon in an attempt to colonize the moon with a Space Station on the Moon. Next, I will launch 2 communication satellites around the combined orbit around the Moon and Earth.
Then, I go to Mars (Duna).
Check it out!