Steinitz Gambit

The Steinitz Gambit, 4. d4, replaces the usual 4. Nf3 with an immediate central grab. Because the knight is not on f3, the h4-e1 diagonal is open, and Black can check with 4...Qh4+, after which the standard reply is 5. Ke2. White concedes castling and stays a pawn down. In return White gains time against the black queen, develops with tempo, and keeps a broad pawn center on d4 and e4. Wilhelm Steinitz, the first World Champion, championed the line, consistent with his view that the king can be a fighting piece. Modern players seldom accept such risk, so the line is rare and generally regarded as dubious. The engine gives Black a slight edge.

After 4...Qh4+ 5. Ke2, the named defenses are the Paulsen Defense, 5...d6, the Zukertort Defense, 5...d5, the Fraser-Minckwitz Defense, 5...b6, and the Sörensen Defense, 5...g5. Online, Black often skips the check. The most frequent replies are 4...Bb4, which pins the c3-knight and pressures e4, 4...g5, which holds the f4-pawn, and 4...d6. White scores well in practice despite the evaluation, and draws are uncommon.