Gipf Project: Lyngk

LYNGK is played with pieces in 6 different colors, each representing a game of the GIPF project.
Actually, there are only 5 active colors, for the 6th color (white mottled, here called "white") is not a color in itself; it can be used as any of the 5 other colors. In the beginning, the pieces of all 5 other colors are neutral, as such they belong to both players.
In the course of the game, each player must claim 2 colors - implying that, from that point on, the opponent may no longer play with these colors.
The goal is to build stacks consisting of 5 pieces of the 5 different colors.
Victory belongs to the player with the most stacks of 5 pieces at the end of the game.