Jerome Gambit: Missing Ingredients

Black is by no means doomed in the Jerome Gambit. (That's a joke. The Jerome has multiple refutations.) However, the defender needs to stick to the basics of defense (or rampant counter-attack) and not neglect an ingredient or two - an oversight can turn the game around and bring about a painful ending.

Wall, Bill - Guest2783012
PlayChess.com, 2018

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+ 

4...Kxf7 5.Nxe5+ Nxe5 6.d4 Bxd4 7.Qxd4 d6 8.Nc3 Nf6 9.O-O Be6 

Black is doing fine. White has to pull a few tools out of his "toolbox", perhaps Bg5 or f4, to keep pursuing his chances.

10.f4 Nc6 11.Qd3 Nb4 

The position of White's Queen is too tempting, Black's Knight must kick it. There is the bonus attraction of the chance to attack White's Rook at a1, so Black dives in. He only risks arriving at an even game, but that is too much to give up - he should have continued the typical castle-by-hand with ...Re8 and ...Kg8.

12.Qb5 Nxc2 13.f5 

This looks like desperation, but White knows what he is doing. 

13...Nxa1 14.fxe6+ 

14...Ke7

Black suddenly realizes that something is up, but 14...Kxe6 or 14...Kg8 were ways to stay in the game. Putting his King where the Knight can be pinned to it is asking for trouble.

15.Bg5 Rf8 16.e5 dxe5 17.Qxe5 Ke8 

This probably looked like some kind of solution, but it is not.

18.Bxf6 gxf6 19.Qh5+ Ke7 20.Qxh7+ Kxe6

Checkmate follows. 

21.Re1+ Kd6 22.Qd3+ Kc6 23.Qc4+ Kd7 24.Qe6 checkmate