What will the flight model be in space?
Airplanes and/or submarines in space (the most common way games do it)? Six degrees of freedom with no friction (the way space really works)? Something in between (like Star Citizen)?
I'm thinking about this from a design point of view. It drastically changes what will work for a spaceship.
Also, will ships have artificial gravity on board? Will we need an element to implement that?