1.e4 d5 2.Nc3

The main line starts with 2...b5 3.Nh3 (or 3.d4 e5 4.exd5 Bd6) and black can choose 3...h6, 3...Bxh3 or 3...f6.

Other possibilities are 2...c6 3.e5 e6 and 2...e5.