Caissa Codex
A00

Formation: Hippopotamus Attack trainer

Back to the opening, all openings to practise or my repertoire

Type a move and press Enter: e4, Nf3, O-O, or from and to squares like g1f3 (e7e8q to promote). The board is also played with the mouse.

Practise the Formation: Hippopotamus Attack

Play White's moves of the line from memory — 1. a3 e5 2. b3 d5 3. c3 Nf6 4. d3 Nc6 5. e3 Bd6 6. f3 O-O 7. g3 — and the trainer plays Black's replies; "Play the other side" turns it around.

Read about the line, its statistics on Lichess and Stockfish's evaluation on the Formation: Hippopotamus Attack page, or pick another opening in the opening trainer.

https://chesscodex.org/train/formation-hippopotamus-attack