Orbiter is a free spaceflight simulator, it's got much more detail on the actual flying and vehicles than KSP, but lacks the building and real time rigid bod...
Orbiter - Vostok 1 - First Ever Manned Spaceflight
Playing Orbiter.... After Reading The Manual
Orbiter 2014 Beta - A Quick Look
Skylab - Orbiter Space Flight Simulator 2010
Part I: The Orbital Elements - Tutorial for ORBITER
Read more about The Geek Mind.