Great polish you have there with the animations and background, the shots synced up with the music pretty well too - although that makes the game really challenging at the end! Nice ramp up of difficulty and introduction of new mechanics. Got confused by the various colors though, I feel 4 is a bit too tedious to remember.
Thanks for the feedback! Yeah the shots were a very rushed late night addition an hour before the end, so they ended up being way harder than they should have been! Yeah I can totally see that over such a short span of levels, it would likely need breaking in over a larger period to be easy to get used to!