Mlotkowski Variation

The Mlotkowski Variation, 3. Nc3, was analyzed by the American master Stasch Mlotkowski in the British Chess Magazine in 1916. White neither takes on e5 nor on f5, but develops and lets Black capture on e4. The point is the reply to 3...fxe4: the natural 4. Nxe4 allows 4...d5, and after 5. Ng3 e4 6. Nd4 Black owns a broad pawn center and good bishops, while the loosened kingside is hard for White to target. White therefore answers 3...fxe4 with 4. Nxe5, and after 4...Qf6 5. Nc4 play transposes to the Leonhardt Variation of the 3. Nxe5 main line.

3...fxe4 is the most frequent reply on Lichess, closely followed by 3...Nf6, which defends against Qh5+ before deciding on the e4-capture; one critical line has White sacrificing on d5 and g6 and reaching an ending with a pile of pawns against a piece. 3...Nc6 leads to the Winawer Defense of the Three Knights Opening, and 3...d6 4. d4 reaches the Philidor Countergambit. The engine gives White a clear advantage, but practical results are nearly balanced.