I did not play for quite a while, but you can fly theoretical any airplane involved in WW2 (almost from every country, e.g. Spitfire Focker Wulf, several types of BF 109, 110...).
And there are even some very experimental air vehicles included, that Germany was developping, but which actually never have been taken place in any battle, like these:
In my opinion, this game is covering the missing part of HD2: Airfighting
But I have to add, that this game is a complex flight simulation.
That means it is not an easy shooter game. Complex abilities are necessary to fly the planes (motor management, propeller pitch, trim...)
Even after playing it one year and by having been trained by an advanced IL2-gamer, I still failed most of my landing operations...
Fortunately (even if the game itself is quite old already) there is still a nice active scene playing it.
They even developed a much better system to handle the gaming server (connection software).
It seems you can get a good overview about the variety of airplanes if you visit this website:
Jaeger Wulfs Downloads