I know this is my 4th consecutive idea but I believe it is more important than the rest of the ones I posted so far. Ship idea:

Currently the ship in game feels like a chonky block floating in space with all that room. I would recommend making it smaller, making the player feel they are inside a normal pop-culture-ish vessel.
Another free game from which you can take example from is Warframe, as when the player logs in, instead of being shown a menu the UI is cleverly spread around the ship in the form of consoles. One more detail I want to add is that the tutorial, shooting range, pre built structures building practice room and the endless corridor your character walks in thile editing skins and loadouts should all be in a holographic chamber instead of being actual rooms.