The RealFlight G6 Demo is a free download from realflight.com. The application provides the user an opportunity to test and evaluate the software prior to purchasing the retail version. The demo version allows one to control virtual R/C aircraft using the keyboard unlike the retail version which uses an I-Controller (a USB pluggable R/C transmitter).
The demo version is very limited in the number of aircraft and flying fields available compared to the retail software. This application does provide 2 aircraft (a trainer and an advanced fixed wing type airplane), 3 helicopters, and 2 flying fields.
The application tests gold for the intended use in Linux but if one has an I-Controller from any retail version G2 and newer, the software will recognize it but only in Windows. When Wine fully supports HID/USB devices, I believe the application will recognize an attached I-Controller in Linux as well. As a consequence, the retail versions will not work under CX Linux yet because the retail versions require/include the I-Controller and therefore does not offer a keyboard as an alternative.
See Tips and Tricks for installation and operation information.