The idea in one sentence
Black counter-attacks e4 instead of defending e5, and aims for a symmetrical, rock-solid position where White's extra move matters little.
♔ White's plans
- Take on e5, then drive the knight from e4
- Use the half-open e-file and quick development
- Castle early and pressure e4 with c4 and Re1
♚ Black's plans
- Counter-attack e4 with ...Nf6
- Kick the knight with ...d6 before taking e4
- Keep the knight on e4 supported by ...d5
Pawn structure. Symmetrical open files; Black's knight on e4 is the piece both sides fight over.
How to learn it
- Read the idea and the plans: every move below serves one of them.
- In the story, ask of each move: what does it do, what does it stop, what does it prepare, why not the other one?
- Drill your side. At the key moves you name the idea first, then play the move.
- Missed moves come back first next time, and in your journal.
The defining moves
- 2...Nf6 attacks e4 instead of defending e5: a counter-attack.
- 3.Nxe5 takes the pawn.
- 3...d6 first: taking on e4 at once allows 4.Qe2, which wins material or a clear edge.
- 4...Nxe4 wins the pawn back; material is level and the position symmetrical.
- 5...d5 supports the knight on e4 with a pawn.
The line follows the moves masters play most (Lichess masters database), each checked by Stockfish 19 at depth 22; where the book move is not Stockfish's first choice, the story says so. Scores are in pawns from White's side: +0.30 is good for White, −0.30 for Black.