Good Moves vs Lesser Moves

To beat a human being a chess program does not have to make a great move every time, it only has to make good move after good move after good move. By way of contrast, if it makes a lesser move followed by a lesser move followed by a lesser move - it risks defeat, as the following Jerome Gambit game shows.

Wall, Bill - AnMon Engine
Palm Bay, FL, 2015

1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. Bxf7+ 

4...Kxf7 5.Nxe5+ Nxe5 6.Qh5+ Ke6 7.f4 d6

Once again the "annoying" or "silicon" defense. (A favorite among computer engines, it works well for humans, too.)

8.fxe5 dxe5 9.Qh3+ Kd6

Black's King goes directly to d6, instead of 9...Ke7 10.Qg3 Kd6 as in Wall, Bill - Comet B50 engine, Palm Bay, FL, 2015 (1-0, 16). The saved tempo improves Black's position. 

10.Qg3 Nf6 

The right idea: development is key for Black, and taking the g-pawn would be dangerous for White.

11.Nc3 a6 12.Rf1 Be6 13.Ne2 Nh5 14.Qf3 Qh4+ 15.g3 Qh3

White now offers a pawn which Black would do well to decline, but computers are known to be grabby. It is a small slip, but small slips add up...

16.d4 exd4 17.Qd3 Qxh2 18.Nxd4 Bxd4 19.Qxd4+ Kc6

Black has to be careful; there is a way to King safety through this messy position, but one error can be fatal. This was the whole idea behind White giving up the h-pawn.

 20.Qc3+ Kd7 21.Bf4 Ke8 22.O-O-O 

Whew, says the human. 

22...Nxf4 23.gxf4 Rg8 

If White has not equalized, he is pretty close. In the meantime, he has his familiar "Jerome pawns" in play against Black's extra piece. The protected, passed pawn at h7 does not get a chance to play a part in the game. 

24.f5 Bf7 25.e5 Qh6+ 26.Kb1 Qc6 27.Qh3 Bd5 28.e6 h6 29.Qh5+ Ke7 30.Rfe1 Raf8 

AnMon is not familiar with this blog, or it would be feeling an eerie sense of deja vu.

31.f6+ Rxf6 32.Rxd5 Rxe6 33.Rxe6+ Kxe6 

Black's King is too exposed.

34.Qf5+ Ke7 35.Qe5+ Kf7 36.Qf4+ Ke7 37.Qe4+ Kf7 38.Rf5+ Kg6 39.Qd3 Rd8 40.Rd5+ Kf7 41.Rxd8 Qh1+ 42.Qd1 Black resigned