Copyright (c) 2002 W. D. Troyka

Blue Nile is played on the following hexagonal board:

DROP - On each turn, each player drops a stone on an empty cell adjacent to the last dropped stone, but not adjacent to any other stone.
GOAL - The player without any valid moves, looses.

An example

If the next player (after the marked blue stone move) moves to cell [2], he will loose (check the parity of the red path).

However, if he moves to cell [1], it's possible to see that the next player will loose (blue dots for the 1st player, green dots for the 2nd).

From the author: You can think of your mission as finding the source of the Nile. You follow the River until it goes no farther. The last player to move is the first to find the source, and that player is the winner. There is a ZRF to play Blue Nile with Zillions.