First click the board to create a random placement of 'apples' (yin-yang symbols). Then click two adjacent positions to place the tail and the head of your little green snake. The Zillions program will do the same with its same black snake.
Move the snake orthogonally any distance by clicking the target positions. All intermediate positions must be empty; but the target position you click may be an apple.

The snakes will grow in length whenever they eat an apple. This give the game an additional twist and makes it more difficult towards the end.

When all apples have been eaten, the longest snake wins. Counters on the left side show how many apples the snakes have eaten.

If you cannot move anymore, you lose (hence you can't wrap your snake's tail around the head of your snake and thus run out of moves, thereby forcing a draw).
If the computer cannot move anymore, the game is a draw (hence you cannot win by making the computer run out of moves).

Variants:
Variants 1 to 3 use different amounts of apples dropped.
In Variants 4 to 6 the systems drops your snake at a random place. This makes these variants slightly more difficult.

There is one alternative piece set available.