'Copter dog is so stinkin' cute, I absolutely adore his propeller hat. But wow, this is tough! I think adding a few more stars or increasing the star timer would make it more forgiving. Basically, have it so that the player needs to be collecting at least every other one. Now, you may have also totally done this, but I'm bad and didn't get that far haha
Great visual style of all your assets! Totally oozing with charm!