Perseus Gambit

The Perseus Gambit leaves the e4-pawn unprotected. White develops the king's knight instead of defending the pawn with 3. Nc3 or 3. Nd2, advancing it, or exchanging it. The same position can also arise from 1. e4 e6 2. Nf3 d5 3. d4. Taking the pawn with 3...dxe4 is by far the most common reply. It is also the engine's first choice and forces the knight to move a second time. Trying to win the pawn back with 4. Ng5 fails: after 4...Nf6 5. Nc3 Bb4 6. Bd2 Qxd4, Black is clearly better. White's usual approach is 4. Ne5, placing the knight on a central square where it is difficult to dislodge.

The natural attempt to drive the knight away, 4...f6, is a blunder because of 5. Qh5+ g6 6. Nxg6 hxg6 7. Qxh8. Black can offer a knight exchange with 4...Nd7. Alternatively, 4...Nf6 guards e4, rules out Qh5 ideas and keeps a comfortable edge. Black may also decline with 3...c5, which leads to a Marshall Counterattack position, or with 3...Nf6. The engine gives Black a clear advantage, and Black scores better than White in online games.