A growing collection of computer games that are freeware, open source or free to play.

ORBITER is a free flight simulator that goes beyond the confines of Earth’s atmosphere. Launch the Space Shuttle from Kennedy Space Center to deploy a satellite, rendezvous with the International Space Station or take the futuristic Delta-glider for a tour through the solar system - the choice is yours.

But make no mistake - ORBITER is not a space shooter. The emphasis is firmly on realism, and the learning curve can be steep. Be prepared to invest some time and effort to brush up on your orbital mechanics.

• 
  Realistic physics. Planetary motion, gravitation
  effects, free space and atmospheric flight are accurately modelled.
  
• 
  You can land your ship at a space port on a planet
  surface, or dock to an orbital station.
  
• 
  High resolution planetary maps provide some nice
  visual effects.
  
• 
  Configurable environment. Users can add planets,
  space ships and space stations to the existing universe, or design a completely
  new solar system from scratch. The Orbiter Software Development Kit contains
  libraries and sample C++ code for addon developers who want to write plugins.
  

You can find many addons for Orbiter at Orbit Hangar Mods, Meadville Space
Center or Dan’s Orbiter
page.

At Virtual Spaceflight you will find tutorials, links to videos and other resourcesm as well as “Go Play in Space”, an Orbiter tutorial ebook.