Nimzowitsch Defense: El Columpio Defense

The Nimzowitsch Defense: El Columpio Defense is a chess opening classified under ECO code B00 in the Semi-Open Games family, where Black responds to 1.e4 with something other than 1...e5, including the Sicilian Defense, Caro-Kann, and Pirc. It is reached after 3 moves: 1. e4 Nc6 2. Nf3 Nf6 3. e5 Ng4. The resulting position leaves white to move.