Damn, I hate to be a critic, because it's clear that this is orders of magnitude ahead of what could/should be expected of a single person working alone and I also really wanted to like it but it just doesn't feel "Star Fox-y" to me.
Some things that I think would help, although I know some or even most of them would require changing FSO's source code itself:
- Brighter ambient light (in Star Fox you usually can see any ship regardless of lighting conditions. Though I guess this is also up to the player to try the lighting options in the launcher)
- Brighter ship colors and light spots on most ships
- The Star Fox style targeting reticle which goes in front of the Arwing and kinda shows the path your shot will follow (Pretty sure that'd be super difficult, though)
- Star Fox style HUD (also difficult, I guess, with the health bar, score indicator and whatnot)
- Indicators for some specific ships (such as your squadmates, the transports and the boss)
- Faster projectiles for the Arwing (possibly for the enemies too)
- Power-up items (No idea how you'd change the primary weapon mid-mission, though)
- Rail segments (I know you tried and couldn't get it to work, but seconding Nightmare, I think that now that you have a solid first mission and most of your Assets done, it could be a good time to look for help from others)
- Handle multi-part enemies like in SF itself. Your fight with Granga looked nothing like a Star Fox boss-fight. He lost Hull Integrity regardless of whether or not you destroyed the barrier-blades, and you never actually shot at each blade, only at the core. It needs the whole weak-spot mechanic of Star Fox bosses and mini-bosses. I'm pretty sure that this is supported in FSO, where you can make the ship immune to damage but the hardpoints damageable.
Again, your work is amazing and what you did is extremely cool, I'm sorry to criticize it, but I hope at least some of my suggestions are easy enough for you to do (if you agree, of course).