Chess Opening Theory/1. e4/1...e5/2. Nc3/2...Nf6/3. f4

= Vienna Game = Black should not play /3...exf4/ because after 4. e5, the black knight has no free square but its home square. The correct move here is /3...d5/.

Theory table
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1. e4 e5 2. Nc3 Nf6 3. f4