Scotch Gambit, Kingside Variation

After 4...Nf6 5. e5, the usual reply is 5...d5, which hits the bishop. The Kingside Variation, 5...Ng4, is the main alternative. The knight sidesteps to the kingside rather than to e4 and joins the c6-knight against the advanced e5-pawn. Black stays a pawn up, with the d4-pawn still standing, but the knight on g4 has no secure retreat and the f7-square loses a defender. The position is also known through the Two Knights Defense move order, 3. Bc4 Nf6 4. d4 exd4 5. e5. The engine considers it roughly balanced, and White scores well in online play.

The most frequent continuation is 6. O-O, completing development and preparing to bring a rook to the open e-file. The sacrifice 6. Bxf7+ is the second choice and the best-scoring try in practice. It drags the king into the open while the knight stands away from the center. With 6. Nxd4 White regains the pawn at once, and results in that line are close to even.