The 1 hour gameplay demostration stream. Apparently a lot was shown and talked about. I haven't watched it myself yet, going to now.
He talks about why they made the first game the way they did, as far as the naval/broadside combat on a 2d plane. He said when they were planning on making Rebel Galaxy they looked at what was supposed to be coming out in the space sim genre, Star Citizen, Elite Dangerous, No Man's Sky, and they felt they would be crushed by the weight of those games if they tried to make a space combat/cockpit game. Fast foward to years later, they looked back on it and they realized that none of those games were anything like what they would have done, so they felt it was a good time to do what they wanted.