Really cool game with good art work to back it up. The music is good but does get a tad repetitive after a while, having the game open up on a title screen with a start, controls, how to play and quit button would be nicer then just immediately starting the game in my opinion.
I also do wish the game would ease the player into how to play a little more, maybe with pop up dialogue from a narrator when meeting the turtle on how to shoot, jump and move and when the turtle dies you could introduce how to swap characters through pop-up dialogue. Overall though it is a really cool interesting take on the theme though. Good job.