Real Zen and fake Zen :)
Zen is a strong Go engine by Japanese programmer Yoji Ojima. On KGS several bots run engine maintaining ranks between 3d and 5d: Zen19, Zen19b, Zen19D and Zen19n. Zen was the first bot to hold a KGS 3d rating for more than 20 rated games in a row, and a blitz version seems to be holding 5 dan ratings in 2011. It was also the first to hold a 2d and 1d rating for more than 20 games, respectively. Hardware used to run Zen19 on KGS: Mac Pro 8 core, Xeon 2.26GHz.
It won the 2009 Computer Olympiad in Pamplona, Spain, running on the slowest hardware among the competitors. It also won the 2011 Olympiad in Tilburg.
Few months ago Zen beat Takemiya Masaki, 9p on 5 stones handicap.
But as you can see from this game, Zen is still far behind from pro level. New Chinese pro(?) AgainstZen easily crushed the program by using his favourite, unusual fuseki
Enjoy the battle!