Formation: Hippopotamus Attack

1. a3 e5 2. b3 d5 3. c3 Nf6 4. d3 Nc6 5. e3 Bd6 6. f3 O-O 7. g3

Formation: Hippopotamus Attack after 1. a3 e5 2. b3 d5 3. c3 Nf6 4. d3 Nc6 5. e3 Bd6 6. f3 O-O 7. g3 87654321abcdefgh

The Formation: Hippopotamus Attack is a chess opening classified as ECO A00, reached after 1. a3 e5 2. b3 d5 3. c3 Nf6 4. d3 Nc6 5. e3 Bd6 6. f3 O-O 7. g3. It is a line of the Formation. Black is to move.

This exact move order didn't appear in our sample of 12.6 million Lichess games: it's a rare line.

Engine evaluation: −1.98 (Stockfish, depth 28; best line 7… e4 8. fxe4 dxe4 9. d4 Ne7 10. c4)

ECO
A00
Moves
13 plies
FEN
r1bq1rk1/ppp2ppp/2nb1n2/3pp3/8/PPPPPPP1/7P/RNBQKBNR b KQ - 0 7
PGN
1. a3 e5 2. b3 d5 3. c3 Nf6 4. d3 Nc6 5. e3 Bd6 6. f3 O-O 7. g3

Analyse with Stockfish · Board image (SVG) · Open on Lichess

Comes from

Anderssen's Opening 1. a3

More Formation lines (all)

Opening names and moves from the Lichess openings dataset; statistics from the Lichess open database, 2026-09 (CC0), sample of 12.6 million games, bots excluded; evaluations from Lichess cloud analysis (all CC0). Master games from The Week in Chess #920–#1664 by Mark Crowther, used with permission.