1.Nf3 e5

2.Ng5 is critical and black has to play 2...f5 (2...f6 3.Nf7 Qe7 4.Nd6 is winning).

The best move should be 3.d4 (most played at top level).

With 3.h4, white prevents counterplay from the black queen and threatens 4.Nxh7 and 4.Nf7. Another line is 3.e4 h5 4.d4.