Hex7x7 is a 2-player alternating move game played on a 7x7 hexagonally-connected board.  On each step, one of the players places a colored marker on an open hexagon.  The goal of the game is for the a player to form a path of markers of its color connecting one side of the board to the other.  The goal of the red player is connect the upper left to the lower right, while the goal of the black player is to connect the upper right to the lower left.  The game is interesting in that one of the two players must win; there is no possibility of a draw.  The clever GDL encoding of the rules for this game is due to Peter Pham.