1.Bd4+ f2 2.Nd2!

2.Rxe6? c5! 3.Nd2 cxd4=

 

2...fxe5

2...dxe5 3.fxe5 fxe5 idem linea principal 4.Be3+-

 

3.fxe5 dxe5 4.Be3!

Try : 4.Bc5? e4 5.g5 e5! 6.Kc3 e3 7.Bxe3 e4 8.Bc5 e3 9.Bxe3 c5 10.Kd3 c4+ 11.Ke2 c3 12.Nf3# mate in 12 moves

 

4...e4! 5.g5! e5

5...c5 6.g6 e5 idem linea principal

 

6.g6 c5 7.Kd5 c4 8.g7 c3 9.g8Q… with

 

a) 9...cxd2 10.Qg4 d1Q+ 11.Qxd1#

 

b) 9...c2 10.Qc8 c1Q 11.Qxc1#