Copyright (c) 2003 Jorge Nuno Silva

This game is played on the following board:

TURN - On each turn, each play may do one of the following actions:
Swap color of an isolated stone (of either color).
KO 1 - The player cannot swap a stone swapped in the last opponent's move.
KO 2 - After two consecutive swaps, it's illegal to swap again.  
Move the upper stone (from a friendly stack of two stones) to an adjacent (orthogonal or diagonal) cell occupied by an isolated friendly stone.
GOAL - Wins the player that stalemates the opponent or achieves a 3 in-a-row (orthogonal or diagonal) with his own stacks of two stones.

Usually, a player will prefer to swap enemy isolated pieces, because he will increase the move range of his upper stones.

An example

White threats a win by swapping c4 (which will be protected one turn by the Ko rule) and then d3-c4 (making a diagonal 3 in-a-row).

However, Black replies with c1-c2 (can win next turn with e3-d2). So White replies d2, then c2-c3 (e3-d4 threat), d4, c3-c4 and the White first threat ended.