Hippopotamus Defense
ECO B00 · 1. e4 Nh6
The Hippopotamus Defense sets up pawns on a6, b6, d6, e6, g6 and h6 with pieces developed behind them. Black waits for White to commit and then breaks with ...c5, ...e5 or ...f5. It looks passive, but it has been used successfully by strong grandmasters, including in world championship play.
Plans for White
White builds a big center and develops quickly, aiming to use the space advantage before Black's position unfolds. Plans include f4 with e5, or a kingside pawn storm with g4.
Plans for Black
Black stays compact, avoids early contact, and chooses the right pawn break later, often after castling. Knights go to d7 and e7, bishops to b7 and g7.
Typical pawn structures
Black's pawns on the third rank, White's in the center: a coiled spring position.
Who it suits
Patient players who want a system that works against almost anything and like defending and counterpunching.
Common traps
If Black waits too long, White's d5 or e5 advances can leave Black without space.