I tripped on across gsb while searching for Cosmic Balance. If you are an old fart like me, you may remember it, it was a game from SSI for the old Atari 800xl. It is a 2d spacer similar to gsb, with some differences.
It had firing arcs for the weapons, marines that you could transport, and gave you control of your ships during battle. It of course was extremely basic, but the gameplay was quite fun.
If there is any interest, I can explain more of the details of it, as there are quite a few that I remember, but am too lazy to post right now.