1.Nf3 f6 2.Nd4 Nh6 3.Nf5 Nxf5 4.e4 e6

White has several possible moves;

5.Na3 c6 6.d4 g6 or 6.c3 g6,

5.d4 g6 6.Bc4 Bb4 7.c3 Bxc3 8.Qd2 h5 or 6...d5 7.Bb5 c6 8.Qd2 h5,

5.c3 g6,

5.h4 h5 6.g4 g5 7.hxg5 h4 or 7.gxh5 g4.