Interesting idea, the movement speed in my opinion could have been a little faster, I have found a glitch with the corners that drastically increases your speed and allows you to skip colliders, the glitch seems to occur when you perform the turtle sprite change, I think this is because the turtle collider is not the same when it is sideways. When you die the game doesn't restart, I think it's great if in your next game that is similar to this one you add it.