Digital Combat Simulator is FREE to download and comes with 2 Free Addon aircraft the SU-25 Frogfoot and the TF-51D. It's made by Eagle Dynamics. Also many 3rd Party Addons are available from compaines like Belsimtek, Polychop, Miltech-5, Razbam.
DCS World includes a vast mission area of the Caucasus region that encompasses much of Georgia - the location of the Russian invasion of Georgia in 2008. As well as a wide range of highly detailed aircraft available for DCS it also offers land combat units, multiplayer , mission generator, pilot log and training missions to name a few.
The accuracy of the models earn high praise from many simulator fans around the globe. The physics of both aircraft and helicopters are of the hughest accuracy and qaulity. Even the manuals are highly detailed and can run hundreds of pages long.