This is about as simple as a game gets.... Arrow keys to control your direction, don't hit your tail or the edge. Collect fruits to grow your snake.
All the code by me, but the original game was by Taneli Armanto The High Score engine was by far the hardest part to create. You can see how to add it into your projects here: https://scratch.mit.edu/projects/323759140 Your score can only be saved if you have the scratcher status.