There are quite a lot of space flight simulators, but most of them are purely science fiction games and don’t always respect physical law.  Orbiter, on the contrary, was invented as a scientifically and technically correct simulator.  There are no space wars or interstellar flights there, but the real behaviour of a spaceship on orbit is shown authentically.  The distribution includes digital models of the Earth, the Moon, all the other planets of the solar system and some of the satellites.  As to spaceships, Space Shuttle Atlantis is available, as well as the International Space Station and the Russian Mir station (in the virtual universe of Orbiter it’s still on orbit, one of the training missions is to undock from the ISS and to fly to Mir).  In training missions, a futuristic Delta-glider rocket plane is used, with atomic engines, that is more easy-to-learn than Atlantis.  The same spacecraft is used for interplanetary flights.  Technically the program allows the users to develop their own spaceships and even their own planetary systems.  Collections of addons are available in the Internet, with those addons one can ‘drive’ virtually everything that has ever flown.

The game therefore is written more for education than for entertainment, so it’s free of charge, but the source code isn’t available and the developers have no plans to support operating systems other than Windows.  Nevertheless, the program runs quite correctly in GNU/Linux via WINE.  It means by the way that it should work also on a Mac, but I didn’t try.  The current version was published in summer 2016, after a seven-year delay.  As it turned out, the developers have been going on to work hard all this time.

You can download the game from its official website.  Two options are available: a MSI installer for Windows and a ZIP archive.  It’s the latter one that should be used in GNU/Linux, but it’s more convenient in Windows as well because it doesn’t need any installation.  It’s enough just to unpack it into any directory you prefer (better not into c:\Program Files) and to run the orbiter.exe file.  The only useful feature of MSI installer in comparison with the ZIP archive is that a desktop shortcut will be generated automatically.

On my own computer, Debian GNU/Linux 8 and WINE 1.6.2 are installed.  The CPU is Intel Core i5-3570K with integrated graphics.  I used an installation guide from here, in short it’s very simple:

1. Install GNU/Linux and WINE.
2. Download a ZIP archive with Orbiter and unpack it, for example, into ~/.wine/dosdevices/drive_c/orbiter.
3. Download from here the file D3D9ClientR7.zip and unpack it into the same directory where you have unpacked Orbiter.
4. Run the command:

   winetricks d3dx10 d3dx9_36 vcrun2005 corefonts

5. Run the Orbiter_ng.exe file (unlike orbiter.exe it uses an external graphics engine).
6. Click Modules, and click Expand all twice.  Enable the D3D9Client checkbox.
7. Check the other parameters and enjoy the game.

My own experiments, however, had different results.  The Orbiter_ng.exe file runs correctly, but any time I try to launch a scenario the game immediately crashes with a message about a fatal error in D3D9Client.  The orbiter.exe file, on the contrary, runs without any errors and doesn’t need any D3D9Client.  There are several issues, but within reasonable.  Both window mode and full-screen mode are available, you can play Orbiter on one virtual desktop (even in full-screen mode) and work on another one, no discrete graphics is required (I play with a maximum resolution for my monitor, 1280×1024).  Hope you will enjoy it, too 🙂