The game begins with both players meeting their 'e file' Pawns in the middle: White moves his to e4 ... Black's to e5.
White decides to bring his King-side Bishop to e2, the square just in front of his King ... Black responds by bringing out his Queen to h4.
White jumps his Queen-side kNight over the front-line of Pawns, onto c3 ... Black chooses to mirror that move by bringing his kNight out to e6.
White's g2 Pawn comes out to threaten Black's Queen, on g3 ... Black's response is to move the Queen just out of reach, but still lurking on g5.
So far, neither side has captured a single piece.
White sends his d2 Pawn to d4 ... Black says "thank you very much" and uses his kNight to capture (x) it.
Black is now awaiting White's move, but can already taste victory - providing White takes the bait!
White DOES take the bait: seeing Black's Queen unguarded and an opportunity for taking this royal prisoner, White uses his Queen-side Bishop to make the capture (x) on g5 ... That leaves Black to wrap up victory by moving his kNight to f3.
White's King has no escape and has no other piece to come to his rescue. It's Checkmate (#), Black Wins (0-1).
... and that's the Hippopotamus Mate.
This is another good example of how sacrificing your Queen CAN be a winning strategy.
- e4 ... e5
- Ne2 ... Qh4
- Nc3 ... Nc6
- g3 ... Qg5
- d4 ... Nxd4
- Bxg5 ... Nf3#