Hive

From the Publisher:

Hive is a highly addictive strategic game for two players that is not restricted by a board and can be played anywhere on any flat surface. Hive is made up of twenty two pieces, eleven black and eleven white, resembling a variety of creatures each with a unique way of moving.

With no setting up to do, the game begins when the first piece is placed down. As the subsequent pieces are placed this forms a pattern that becomes the playing surface (the pieces themselves become the board). Unlike other such games, the pieces are never eliminated and not all have to be played. The object of the game is to totally surround your opponent's queen, while at the same time trying to block your opponent from doing likewise to your queen. The player to totally surround his opponent's queen wins the game.