Flightgear is a
free,
open source flight simulator released under the
GPL and with contributions from people all around the internet. It was born as many
open source projects are, someone had an
itch, and the need (and
talent) to
scratch it. In this case, the itch was a growing
dissatisfaction with the available
commercial flight simulators and
closed nature.
What the flight gear team wanted to create was a flight simulator that was open so that anyone could contribute, and was not proprietary like many of the commercial software offerings. Having a well designed system that allowed modification and enhancement. Many of the team members, from all over the world, had different goals for the project, with varying degrees of complexity.
One of the big differences between flight gear is the variety and complexity of scenery available. There is a graphical download tool for downloading scenery that appears to have most of the earth covered, excluding a few large ocean regions and some sections of the poles. To use the scenery is very simple. Just download a tarball and decompress it in the right spot and then start the program and tell it where you want to go by airport ID.
Flightgear is a well organized, well executed program that is rich with options and realism. While most hard core military sim addicts will probably not enjoy it as much as they would blowing things up, anyone who is looking for a way to fly a civilian aircraft through a rich and complete world will probably enjoy this program.
Sources
Flight Gear website at http://www.flightgear.org