Leonardis Variation

The Leonardis Variation, 1. e4 e5 2. d3, is one of White's unusual second moves after 1...e5 and is classified under ECO C20. The pawn move protects e4, although Black has not yet attacked it, and opens a diagonal for the c1-bishop. It also shuts in the f1-bishop, develops no piece, and costs a tempo if White later decides to push the pawn on to d4. For these reasons it is generally considered to hand over the initiative that the first move normally confers.

The resulting structure is essentially the Philidor Defense with colors reversed. Black can occupy the center freely by developing a knight and following up with ...d5. A typical sequence is 2...Nf6 3. Nf3 Nc6 4. Be2 d5 5. Nbd2, which corresponds to the Hanham Variation of the Philidor with the colors swapped. Here White's extra move does little to change the passive character of the setup, and Black is regarded as standing slightly more comfortably.

White has two main ways to avoid placing the king's bishop passively on e2 behind the d3–e4 chain. One is a King's Indian Attack formation, with g3 and Bg2 aimed at the long diagonal. However, the reference literature considers 1. Nf3 d5 2. g3 a more accurate route to that setup, because it prevents ...e5. The other is an early f4, a kind of Vienna Gambit that lacks some of the original's punch. It keeps the balance but is played less often.

The most frequent reply is 2...Nc6, chosen in about two games out of five, followed by 2...Nf6 and 2...d6. The engine also lists 2...Bc5 among its preferred moves. A rarer try is 2...f5, known as the Clam Variation or the King's Gambit Reversed, in which Black strikes at e4 at once. Despite its modest reputation, the variation reaches a large number of online games and ranks among the more frequently seen named openings. Results are almost perfectly even, with few draws, and the engine assesses the position as balanced.