Jerome Gambit quick checkmate

The new short YouTube video "Jerome Gambit quick checkmate" is entertaining and raises a number of questions that are great fun to try to answer.

Stockfish - Cramlingbot

Chess.com, 2021

So, we have a game between two computer chess engines, the second representing Anna Cramling, Twitch chess streamer.

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+ 

4...Kxf7 5.Nxe5+ Nxe5 6.Qh5+ Ke6 

7.f4 Qf6 8.Rf1 Kd6 

This is an unexpected move.

More usual would have been 8...d6, offering to return a piece with the same idea as in the "silicon" or "annoying" defense (1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+ Kxf7 5.Nxe5+ Nxe5 6.Qh5+ Ke6 7.f4 d6). Stockfish 15 then shows that 9.fxe5 Qg6!? is the only way for Black to continue to maintain his advantage.

The Database has 6 games with 8...d6. Black won 5 of them.

What to make of Black's 8th move? It looks like a "mouse slip", a very human type error. Computers don't "mouse slip" do they? 

Actually, there is a funny Tweet that suggests that the Cramlingbot is capable of such an error

The

@AnnaCramling

bot on

@chesscom

is pretty accurate, they even programmed it to mouse slip in the endgame.

9.Nc3 

The right choice of moves.

Grabbing a piece with 9.fxe5+ Qxe5 10.Qxe5+ Kxe5 or 9.Qxe5+ Qxe5 10.fxe5+ Kxe5 would take the Queens off of the board, leaving White with only one pawn for his sacrificed piece, and Black with a well developed and relatively safe King.

White was successful after 9.d4 Bxd4? 10.fxe5+ Bxe5 11.Rxf6+ Bxf6 12.Bf4+ Ke7 13.e5 d6 14.exf6+ Nxf6 15.Qe2+ Kf7 16.Nc3 Bf5 17.Kd2 Rae8 18.Qc4+ Be6 19.Qxc7+ Re7 20.Qxd6 Rd7 21.Re1 Rxd6+ 22.Bxd6 Rd8 23.Kc1 Rxd6 24.h3 Nd5 25.Ne4 Rd7 26.Ng5+ Kf6 27.Nxe6 Re7 28.g4 Rxe6 29.g5+ Kf7 30.Rf1+ Ke7 31.h4 Nf4 32.Rxf4 Re2 33.Rb4 b6 34.Ra4 Kd6 35.Rxa7 White was better and won on time, jpayero - nathanael31, 1 0 bullet, lichess.org, 2022.

However, 9...Nd3+ 10.cxd3 Qxd4 instead would have given Black an edge. 

9...Qe6 

Another curious move. (There are ways to make a smart computer dumber. See "Jerome Gambit: Artificial Wha?")

Certainly Black could have played 9...Nc6, 9...Nb6 or 9...Nf7, instead, planning on meeting 10.e5+ with 10...Nxe5, returning a piece. That would be a reasonable plan, but The Database has no games with any of those 3 moves.

Another idea would be to move the King again, i.e. 9...Kc6 10.fxe5 (10.b4!?) 10...Qg6 11.Qe2 a6? (11...b6) 12.Qc4 (12.b4!?) 12...Qe6 13.Nd5 Ne7?! (13...b5) 14.d4 b6 15.Nxe7+ Qxe7 16.Qd5+ Kb5 17.c4+ (17.a4+ Ka5 18.Bd2#) 17...Ka4 18.b3+ Ka5 19.Bd2 checkmate, jpayero - nathanael31, 3 0 blitz, lichess.org, 2022.

A reasonable choice was 9...c6, which appeared in 2 games: 10.fxe5+ (10.Ne2 g6?! 11.fxe5+ Qxe5 12.Qxe5+ Kxe5 13.b4 Bxb4 14.Bb2+ Black resigned, VM5715080 - draveilpb, 10 0 blitz, lichess.org, 2021) 10...Qxe5 11.Rf5 Qd4 (11...g6?! 12.Rxe5 gxh5 13.Re8 Kc7 14.d3 b6 15.Bf4+ d6) 12.Qg4 Qg1+ (12...Nf6) 13.Rf1 Qd4 14.d3 Nf6?! (14...Kc7) 15.Bf4+ Ke7 16.Qxg7+ Kd8 17.Qxh8+ Ke7 18.Bg5 Kd6 19.Bxf6 Qe3+ 20.Ne2 (20.Kd1 Qd4 21.Qe8 Qxf6 22.Rxf6+ Kc7 23.Qe5+ d6 24.Rf7+ Kb6 25.Qe7 a5 26.e5 Ka6 27.exd6 Bg4+ 28.Kd2 Rb8 29.Qc7 Ba7 30.d7 Rd8 31.Qxd8 Bc5 32.Qa8+ Ba7 33.d8=Q Bc8 34.Qaxc8 Be3+ 35.Kxe3 h5 36.Qxb7#) 20...Bb4+ 21.c3 Kc5 22.d4+ Kc4 23.cxb4 Kd3 24.Rc1? (24.Rf3 Qxf3 25.gxf3 Kc4 26.Qf8 b6 27.a4 c5 28.Qh6 cxd4 29.Qd2 Kb3 30.Ra3+ Kc4 31.Qxd4#) 24...Qxe2 checkmate, carlson85 - E-Shaposhnikov, 1 0 bullet, lichess.org, 2020) 

10.d4 Bb4

This move does not help things, but 10...Bxd4 would lead to complications and the loss of a piece after 11.Nb5+ i.e. 11...Ke7 12.Nxd4. It turns out that Black can not protect the Bishop with 11...Kc5 because 12.Nxd4 Kxd4 13.Be3+ would lead to checkmate. (12...Qd6 would be better than the recapture, but would drop the piece.)

White's attack now builds and ends in mate.

11.fxe5+ Ke7 12. Bg5+ Nf6 13.exf6+ Kf8 

14.fxg7+ Kxg7 15.Bh6+ Kg8 16.Qg5+ Qg6 17.Qd8+ Qe8 18.Qxe8+ Bf8 19.Qxf8 checkmate