Copyright (c) 2002 Jorge Gomez Arrausi

Unlur is played in an empty hexagonal board:

LINE - a connected group of stones of the same color which is connected to two opposite sides of the board.
Y -  a connected group of stones of the same color which connects three non-adjacent sides of the board.
PIE RULE - Players alternately drop black stones on empty cells until one player passes. When one player passes the other player will be White and he has to make White's first move. After this, the game continues normally.
The stones, in this phase, cannot be placed on the edges nor in the corners.
TURN - On each turn, each player drops a stone (of his color) on any empty cell. 
GOAL - White wins if he makes a line, Black wins if he makes an Y.
However, if White makes an Y without making a Line, he loses. Black loses of he makes a line without making an Y.

This ingenious PIE rule is necessary, because White has a much easier task than Black.

An example

Players dropped 4 black stones. Then, one player passes and becomes Black. The usual alternating turns start with a White move.

Unlur was the 2002 Game Design Competition winner (check the other finalists). Check the game's website.