Hey I really liked this. Reminded me a tiny bit of Lander on the Archimedes, Hardwar (underrated!), Wing Commander-y visuals.
The extensions suggest themselves - some progression (financial) beyond merely guild hierarchy; some adversarial element (could be economical like bidding for routes.)
Only bit I struggled with was the car-like handling when you turn left and right; I would expect you to orient using yaw axis and then have to use thrust to change your velocity vector. But it certainly is simpler the way you have it.
The "car-like handling" is still physically accurate - thrusters automatically align your velocity vector to match your view direction. You can think of it as simply an interface - view direction is both a command and a display.