Copyright (c) 1993 Jean-Claude Rosa

Troll is a two player game played on an empty 8x8 square board:

EDGES - Each players owns two opposite edges, say, first player has top and bottom edges, while second player has left and right edges.
DROP - Each player drops one of his stones on an empty cell.
If at least one opponent stone is between that stone and another friendly stone (orthogonal or diagonal), then all opponent stones that were between those stones flip its color.
Stones cannot be dropped on the opponent's edges (including corners).
GOAL - Wins the first player who manages to do a path connecting his two opposite edges.
Two tiles diagonally aside are not continuous in a path.
The corners belong to both edges.

An example

White has not won yet! He does not have an orthogonal chain of stones between his two edges. He might win by dropping at one of the cells [1]. If it's Black's turn, he can defend by playing at cell [2].