Definitely fun game!
It was a pleasant surprise when I managed to join a body. At first I thought they were enemies too. I really liked the artwork, it looked neat!
I would have only changed that when you are inside a body or in the tank you could aim freely or at least 180º in the direction you are looking, instead of having to look up. Maybe also that the tank couldn't jump.
The bosses were cool and a nice touch! Great job!