you are a little worm, your body is the "o"s on the screen
and your head is the "@".
As in the game
you move with the hjkl keys.
If you dont press any keys, you continue in the direction you
last moved. The upper case HJKL keys move you as if you had pressed
several (9 for HL and 5 for JK) of the corresponding lower case key
(unless you run into a digit, then it stops).
On the screen you will see a digit, if your worm eats the digit is will
grow longer, the actual amount longer depends on which digit it was
that you ate. The object of the game is to see how long you can make
the worm grow.
The game ends when the worm runs into either the sides of the screen,
or itself. The current score (how much the worm has grown) is kept in
the upper left corner of the screen.
The optional argument, if present, is the initial length of the worm.