Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...f5/4. Nc3/4...fxe4/5. Nxe4/5...Nf6/6. Qe2

6...d5 is a beautiful freeing move in most 1.e4 e5 openings, and here Black gets it for free thanks to the awkward knight on e4.

6...Qe7 makes less sense, because if the queen is planning to capture on f6 then it's a waste of a tempo, and if the g-pawn is planning to capture on f6 then the queen isn't needed on e7 to defend the e-pawn because the new f-pawn will be defending it.