Man Oh man, this game is a dream come true. I now think this game is perfectly balanced as far as difficulty is concerned. When the SU 27s go in to spiral loops in hopes of evading oh man I just couldn't stop smiling. It was absolutely amazing! The weapons are going to need some more time. Especially the High Manuever Missiles. They will literally follow an enemy to 3+ minutes if they miss the first go around. Maybe dial that down to 1 minute lol. Optimization is wonderful my 970 is running it well on high. I do think that the post processing may be a bit extra. I'd probably say that is a bit on the extreme side, but it makes the game look just that much better. It is a bit hard to run that and record though on my 970 got me thinking of upgrading. I think a big thing missing now is actually a warning alarm for collision or at least a pull up proximity alert. I've crashed a few times now that its completely pitch black into a storm clouds.
That being said this game is perfect for VR. You need to make some strides into that front because of how easily I converted this game into VR. Your game is amazing and I'm certain if you just spent about a weeks worth of work you can code it for Steam VR.
I used TrinusPSVR it literally took me 10 minutes to configure to work with your game.