Neat idea! The music is fairly catchy and the sounds work well! I like the idea of swapping between each guy, but then I noticed that you only "lose" if both of them die, which sort of ruins the "tension" of the game since you basically never have to switch, you can just choose to play one or the other. If you died when either one died, it would be more interesting.
Also the alien's hitbox felt very unforgiving, and the game threw situations where it was impossible to save both of them at once.