Copyright (c) 1998 Great American Trading Company 

This game is played on the following board.

Each player also starts with 10 stones of his color, plus 10 neutral stones.

TURN - On each turn, each player must do one of the following things:
Drop a neutral stone on an empty cell
Drop a stone of his color over any empty neutral piece.
Pass if it is unable to make a valid drop.
GOAL - Wins the player that manages to get a 3 in-a-row of his color.
If the first player drops all his stones without winning, he looses.
An example

In this position, the player that moves next wins by dropping one of his stones at cell b2. Red by making a direct 3 in-a-row, Black by creating an open 2 that cannot be stopped by the next red move.

Since there are 20 neutral stones and only 19 cells, the board is sooner or later (if it doesn't end before that) totally filled. 

Each player must keep a balance between neutral and colored stones. Running out of either is bad. No neutral stones implies that colored stones should be dropped on potential bad cells (the opponent can play neutral stones exactly on those places). No colored stones left to drop almost always means disaster.