I have annotated the game Raset Ziatdinov - Joel Benjamin, Philadelphia (World Open) 1999 as part of my continuing series on GM Benjamin's opening innovations. Previous posts discussed The Brooklyn Defense and the Nimzovich with ...e5.
In his book American Grandmaster, GM Benjamin says he was surprised to be approached at a tournament by a young chessplayer who said she was a great fan of his opening ideas in the Pirc -- especially the line he calls "the Classical Hippopotamus" beginning 1.e4 d6 2.d4 Nf6 3.Nc3 g6 4.Nf3 Bg7 5.Be2 O-O 6.O-O e6!? Why he should be surprised to be associated with this line, though, is beyond me since he annotated several of his games with it for Informant #74 and was clearly its most prominent originator. The move has since been used by such well-known Pirc aficionados as GMs Tiger Hillarp Persson, Jonathan Rowson, and Ruslan Ponomariov. Like other versions of the Hippopotamus, it is currently quite fashionable, but games like Ziatdinov-Benjamin did a lot to inspire the trend.
One reason Benjamin calls it a Hippopotamus is because Black could easily set up a standard Hippo formation, as in Weemaes-Horvath,Val Thorens 1999 which went 1.e4 g6 2.d4 Bg7 3.Nc3 d6 4.Nf3 Nf6 5.Be2 0-0 6.0-0 e6 7. Re1 Nc6 8. h3 a6 9. a4 b6 10. Be3 h6 11. Qd2 Kh7 12. Rad1 Ne7 13. Qc1 Bb7 14. Bd3 Nd7! (see diagram).
The Classical Becomes a True Hippo
Like its spiritual cousin the Hedgehog, the Hippo is above all a flexible formation that waits to respond to White's aggressive advances by seizing whatever squares or lines the attacker surrenders. You might thus see it as a type of jujitsu stance, ready to absorb whatever blows White might throw while striking back at whatever weaknesses his attack exposes. Black can also consider striking some blows in the center himself with any of the center pawns. The Hippo is especially effective out of the Classical Pirc where White has committed his Knight to f3 and therefore foregoes the possibility of a quick f4-f5 push, which is one way of attacking the Hippo that I find effective as White.