Sometimes it only takes a little bit...

The following game shows that sometimes it takes only a little bit of wandering off the path for Black's game in the Jerome Gambit to suddenly to bad. Philidor 1792 wraps up quickly thereafter.

Philidor 1792 - Guest388983
3 0 blitz, PlayChess.com, 2014

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+ 

4...Kxf7 5.Nxe5+ Nxe5 6.Qh5+ Ng6 

7.Qd5+ Kf8 8.Qxc5+ Qe7 9.Qe3 Nf6 10.Nc3 d6 11.0-0 Kf7

12.f4 Re8 13.f5 Ne5 14.d3 Bd7 15.Qg3 Kg8

Black has done well, castling-by-hand and hanging onto his piece for two pawns advantage. Suddenly, his game turns sour.

16.Bg5 Qf7

It is not automatically apparent that this move is wrong, but Black's game suddenly grinds to a halt.

17.Bxf6 Qxf6 18.Nd5 Qd8 19.f6

 Black's King is in danger, and his pieces are curiously ineffective here, as Houdini showed me. Probably he should try 19...g6, and when White threatens to bring his Queen to g7 for mate, he can answer 20.Qh4 with 20...h5. The continuation 21.Qg5 Kh7 follows the same idea, when White can then win the exchange with 22.Ne7 Rxe7 23.fxe7 Qg8 

analysis diagram



White can now put a full cramp in Black's position with 24.Rf4 Qg7 25.Raf1 Be8 26.Rf8 when it will take a lot of work to untangle Black, for example 26..Rb8 27.Qf6 Qxf6 28.R1xf6 Nc6 29.d4 a6 30.d5 Ne5 and White's bind still holds. 

19...Ng6 20.f7+ Black resigned

Black will be down only the exchange and a  pawn (after 21...Kf8 22.fxe8+/Q Kxe8), but his King will be at risk, and White will have the initiative.