the same snake, but senile
I was going to write just what Simonp did, The controls dont respond quickly enough, when stroked real fast sequentially, wich is essential in snake.
Try runing left->right, then press UP then LEFT, only LEFT will the ackownledged.
Maybe its related to this other bug i found:
if the snake is only 2 squares long, you can double back, and you wont bite yourself... (but maybe its been always like that? dont remember) Cause that behavior would be ocnsistent to that when the head is adjacent to the last segment, and occupies such position at the same time the last seg moves forward, which IS a valid situation...
So, add sound effect, more surqes in the arena, enemy snake and youre set