A very cool and challenging idea. I made it to the boss (or 2 bosses) and I like how I had to keep an eye on each of my ships to keep track of what's happening.
My criticism is that certain important elements of the game aren't explained, such as the powerups and the controls. Admittedly, I was able to pick up on these stuff as I played, but some kind of tutorial would've been nice.
Overall, I had fun playing it. Well done.