Great game so far!
I think I found a bug: In the first round, I got my fighter captured, and then the boss, in formation with one other fighter and my captured ship, swooped back down for another run. As it came down, I shot and missed the boss, but hit the fighter that was coming down with it (the alien, not my captured ship), and...I got my captured ship back, despite the fact that the boss was still alive! In fact, I was so thrown by this that the boss hit and killed my original ship, but I was able to continue play with the released ship.
Weird stuff, but a great achievement otherwise. Thanks for all the hard work.