Barnes Opening: Hammerschlag is a chess opening with the ECO code A00, part of the Barnes Opening family. It goes 1. f3 e5 2. Kf2. White opens with 1. f3 (the Barnes move) and Black answers 1... e5. After 3 moves it is Black to move. The lesson on the board explains every move of the line and lets you play it yourself; it is free.
White starts with 1.f3, one of the worst first moves. It weakens the king and takes the best square from the g1 knight.