I'm wondering why you would make a non-3D interface in unity (which was practically made for 3D). On another note: add buttons to make the front face spin, as it is, you have to make a full turn top, turn the top layer and then a full turn down.
the tech point number doesn't seem to get it's original size when you gain one... 20 minutes into the game, the number is taking up a quarter of the screen...
i'm guessing you make every object that enters the screen check if any of the bullets collide? this is really bad because when you have too many bullets you get increasing amounts of calls to the function... maybe optimization is in order?