Orbiter is a flight simulator able to take you even to the limits of the atmosphere. Take off in your space module from Kennedy Space Centre, launch a satellite, pass by the International Space Station, or take a flight through the Solar System in a modern Delta-Glider. The choice is yours and only yours.
Orbiter puts all the emphasis on realism, both in the graphics and in the general game development. The learning curve is surprisingly smooth, and so get ready to invest some time improving your flying and learning the mechanics of orbiting.