Congrats for this, this is a massive amout of work!
I got a bit frustrated by the controls of the ship, but I guess that is somewhat part of the game :p It got waaay better when I plugged in an XBox controller though (kudos for dealing with multiple input systems btw).
I still found it extremely hard to hit enemy ships. They were simply too far away, the projectiles are quite slow, and the time it took me to get closer they were already on their way out :/
And I got a bug where I got like -2 million credits after finishing a mission :o
Amazing job on the UI and the 3D scenes, the menu is quite complex and neat. The simple explanation text at the beginning is a nice touch to get into it!
Anyway, good luck with the ratings ;)