1.Nf3 f6 2.Nd4 Nh6 3.Nf5 Nxf5 4.Nc3 c6

White's main moves are:

5.d4,

5.e4,

5.Nd5 cxd5 6.e4 d6 7.Bb5 Nc6 8.d4 h5,

5.Ne4 e5 (or 5...Na6).