OK concept...

...but the game itself could be improved upon. First off, the size and color of the leaves make them hard to see when they appear on certain areas of the background. Also, it would help if the instructions came at the beginning, and then the player was prompted to begin. As it was, I stared at the screen for a moment until I realized the little blue square was the "snake." On top of that, the area at the bottom wasn't pleasing to the eye in general.

It seems like you spent some time with the programming, so if you make it more user friendly and pleasing to the eye, it'll be fine (for a game of snakes.)