I have maintained The Database of Jerome Gambit games to help me get a sense of how certain lines or moves succeed or fail - from a practical (i.e. over-the-board play) point of view.
I have used chess analysis engines (currently Stockfish 8) to get a sense of how certain lines or moves are "objectively" strong or weak.
It is a joy when both the practical and the analytical agree. It can be confusing when they don't. Take the following game. It left me a bit confused...
Petasluk - givemeabreak
5 0 blitz, FICS, 2017
1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+
4...Kxf7 5.Nxe5+ Nxe5 6.Qh5+ Kf6
Including this game, Petasluk has reached this position 7 times according to The Database (which, I admit, need some updating). Before this game he was 2-1 with the followup 7.Qf5+ and 2-1 with 7.f4. This compares with statistics from the whole Database - White scores 80% (35 games) with 7.Qf5+ and 80% (10 games) with 7.f4.
So, from a practical point of view, 7.Qf5+ and 7.f4 are both good move choices, according to Petasluk's experience; and both are excellent choices from the experience of those represented by The Database.
7.f4
So, no surprise here.
Yet the computer analysts, starting with Stockfish 8, leap directly for the straightforward 7.Qf5+ Ke7 8.Qxe5+ Kf8 9.Qxc5+ picking up the two sacrificed pieces.
Why the discrepancy?
7...g6
Well, here is one reason: the defender in this game is human, and humans make mistakes. The alternative 7...Nc6, withdrawing the attacked piece, allows White to only recover one of his sacrificed pieces: 8.Qf5+ Ke7 9.Qxc5+ Kf7, with pressure on the enemy King, but not full compensation for his offerings.
8.Qxe5+ Kf7 9.Qxh8 Black resigned
Well, it looks like "Practical Experience 1, Computer Analysis 0".
But that is not the whole story. A number of Petasluk's games continued from the above "final" position:
9...Nf6 (9...d6 10.Qxh7+ Kf8 11.d3 Qf6 12.Qxc7 Be3 13.Nc3 Qxf4 14.Rf1 Qxf1+ 15.Kxf1 Bxc1 16.Rxc1 Black resigned, Petasluk - douthy, FICS, 2015; or 9...Qe7 10.Qxh7+ Kf6 11.Qxg8 Qxe4+ 12. Kd1 d5 13.Qh8+ Kf5 14.Qh3+ Kxf4 15.Rf1+ Kg5 16.Qg3+ Bg4+ 17. Rf3 Re8 18.c3 d4 19.h3 Qe2+ 20.Kc2 d3+ 21.Rxd3 Qd1 checkmate, Petasluk - kosten, FICS, 2013) 10.Qxd8 Black resigned Petasluk - skaks, FICS, 2015 and Petasluk - kaliz, blitz, FICS, 2014 Be7 11. Qh8 11... b6 12. e5 Bb7 13.Qxa8 Bxa8 14. exf6 Bxf6 15. O-O Be4 16. d3 Bc6 17. Nc3 Black resigned, Petasluk - TaccyChan, FICS, 2007.
That's 4 wins and 1 draw. More support for practical considerations.
But I expect the "Wait 'til next time!" bunch will want to look closer at 7.Qf5+.
(Where did the "extra" games come from? Petasluk - TaccyChan, FICS, 20017; Petasluk - Kosten, 2013 and Petasluk - douthy, FICS, 2015; all transposed from 6...Ke6.)
The second Jerome Gambit game recently sent by Vlasta Fejfar looks so incredibly "normal" (by Jerome standards, anyhow) it was hard to believe that it became completly "unusual" before a dozen moves.
What was "normal", however, was Black's increasing uncertainty or confusion on defense, followed by increasing pressure by White's "Jerome pawns" - followed by a win by the attacker in under 30 moves.
vlastous - mostafa-salman
internet, 2017
1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+
4...Kxf7 5.Nxe5+ Nxe5 6.Qh5+ Ng6
7.Qd5+ Ke8 8.Qxc5 d6 9.Qe3 Qf6 10.O-O N8e7
And, just like that, we have reached a position that seems familiar, but appears in only 2 other games in The Database.
I could make this sound quite incredible by pointing out that The Database has 55,650 games - but that would be a bit unfair; so let me say that, of the 12,823 games in The Database that start with 1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+ - well, there still are only 2 other examples.
11.f4 Nc6
What's not to like about this move - which is a novelty?
It improves upon a couple of earlier games:
11...Kf7 12.f5 Ne5 13.d4 Nc4?! 14.Qb3?! (14.Qd3!?) 14...b5 (14...Qxd4+!?) 15.Nd2?! Qxd4+ 16.Kh1 Ke8? 17.c3? (17.Qxb5+!?) 17...Nxd2 White resigned, shugart - douthy, lightning, FICS, 2014; and
11...Bd7 12.f5 (12.d4!?) 12...Ne5 13.d4 Ng4?! 14.Qd3 a6 15.h3 Bb5? 16.Qc3? Bxf1 17.hxg4 Bb5 18.g5 Qf7 19.Qxc7 Rc8?! 20.Qxd6 Qc4 21.f6 Qf1+ (21...gxf6 22.gxf6 Ng6) 22.Kh2 gxf6 23.gxf6 Ng6 24.Qe6+ (24.Nc3!?) 24...Kf8? 25.Bh6 checkmate, perrypawnpusher - LeiCar, blitz, FICS, 2010.
12.c3 Bd7 13.d4 Kd8
Understandably, Black's King wants to get off of the soon-to-be-opened e-file.
14.d5 Nce7 15.c4 Rf8 16.Bd2 Qf7
Likewise, Black's Queen - which has been helping hold back White's e-pawn - decides to get off of the a1-h8 diagonal, where White's dark-squared Bishop appears to be heading.
White's central "Jerome pawns" are threatening to advance and cause problems, and it is not surprising that Stockfish 8 already sees the first player as having the advantage.
17.Nc3 Qf6
Back on the diagonal - but it is also on the file! White strikes.
18.e5 dxe5 19.fxe5 Qb6
Black's Queen could not capture the e5 pawn because of 20.Rxf8+.
20.c5 Rxf1+ 21.Rxf1 Qxb2
Slipping behind enemy lines (pawns) to grab a pawn. Very dangerous!
22.e6 Be8 23.d6 cxd6 24.cxd6 Qb6
25.dxe7+ Nxe7 26.Qxb6+ axb6 27.Bg5 Rc8 28.Nd5 Black resigned
White's pieces are tied up and tied down, and material will be lost.
