Turning Snake into a puzzle game is a great idea! The shrinking mechanic adds a really interesting twist too. I also appreciate some of the general twists on the classic Snake formula, like giving the player a bit of grace time before the failure state!
Less appreciated is the smoothed movement, though... it creates some severe input lag which honestly killed the game for me, the snake was consistently turning a full grid tile after I wanted it to, which made later levels extremely difficult even after I figured out the solution.