Stanley Variation, Meitner-Mieses Gambit

This line comes from the symmetrical 2...Nc6 3. Bc4 Bc5 move order. White's 4. Qg4 attacks g7, and 4...Qf6 defends it while also hitting f2, which is now guarded only by the king. With 5. Nd5, White does not protect the pawn. The knight attacks the black queen and eyes c7, where a check would fork king and rook. If the queen moves off f6, g7 also loses its defender. Black usually accepts with 5...Qxf2+. The check forces White's king to d1, so White gives up a pawn and the right to castle. In return Black's queen is far from home and the queenside is exposed to the knight. The play is forcing and depends on calculation.

The engine still gives White a slight edge, and its top choices are the captures 5...Qxf2+ and 5...Bxf2+, followed by the retreat 5...Qg6. In the Lichess sample White scores heavily, winning 69% of games. Black fares worst after 5...Bxf2+ and 5...Qg6.