Copyright (c) 1973 Copp Clark Publishing Company

This game is played on a 7x9 board with the following setup:

ARENA - The middle 3x3 area.
TURN - On each turn, each player moves a friendly stone.
Stones (called frogs in the original rules) move like the chess horse (i.e., to the nearest cells not in the same row/column/diagonal).
Captures are by replacement and are not multiple nor mandatory.
GOAL - Wins the player that makes a 3 in-a-row inside the arena and is able to maintain it during one turn.
If both players have less than three stones, the game is a draw.
An example

Green's turn. If he moves f4-d5, Green makes a 3 in-a-row which is broken by Blue's c7:d5.

So, Green must first move b1-c3 in order to reply to c7:d5 with c3:d5 and winning the game.

Blue does not have enough time to move another horse to protect that position.