Okay i absolutely love snake. it is one of my all time favorite classic games to return to and play. I have to say this idea... BRILLIANT. you just needed to adhere a bit more to the snake limitations, i think and this would've been really something else. As it is, you can trace over yourself, which is so un-snake-like.
also on my 3rd retry, i couldn't push the block on screen 4. Really love this idea, might use it myself for a game some day.