Copyright (c) 1997 Bryce Wilcox

The game is played on a initial empty 3x7x5 hexagonal board.

DROP - On each turn, each player drops a stone into an empty cell.
SNAKE - A snake is a string of stones of the same color, with the next restrictions:
Each stone is adjacent to either one or two other stones of the same color. So, a snake has no branches in its body.
There are no sequences of three adjacent stones all in a line in a snake.
GOAL - When both player pass, wins the player with the longest snake.

An example

White should play at cell [1] in order to avoid the connection of both Black snakes. Black then, could not join them, since it would have stones with more than two adjacent friendly stones.

Some notes from the author:

About some variations:
The John Tromp alternate scoring rule: each snake is worth 2x, where x is its length.
The "no weenies" alternate scoring rule: each snake is worth x-n, where x is its length and n is a constant.
The "long straight snakes" alternate snake definition: ignore the all-line restriction in the traditional definition of a snake. This would completely change game play. As far as I know nobody has tried it yet. 
The "loops bonus" rule: if you place a stone which forms a snake in which all stones are adjacent to exactly two other snake-stones (i.e. a loop), you get to make another move. You might choose to allow snake eggs as loops for this rule!
New game: a descendant of Squirm which allows you to move stones...
Getting the first turn isn't necessarily an advantage, because when you play you are committing to positions that your opponent can use against you. Your own stones become poisonous to you in certain situations, so it might well be that playing second is more advantageous. This will be determined by experience, I guess.