Off the bat: the art style is unique and the music holds up. Presentation on the whole was impressive, definitely one of the more enjoyable games to look at.
As far as actual gameplay goes, I think you have the makings of something here, if a little underdeveloped. I didn't totally buy the two-sided turtle as fitting with the theme, though I like the idea of having two avatars who can interact with different areas, something in that Fireboy & Watergirl lineage.
On the glitch side, the turtle has a tasty habit of getting its head stuck in the wall, requiring a restart. This might not be so frustrating with faster movement and checkpoints, anything to get you back to where you were faster.
Overall, I had a fine time, I could see a satisfying light puzzle game coming out of this.