Amazing tactical game

[Laskos]

At higher depths (d=30 and up) 27...Qd7 is preferred, but it's still a +/-:

Code: Select all

Analysis by Stockfish 150516 64 POPCNT RCEC:

[...]
27...Qd7 28.b3 b5 29.Nxf6+ Bxf6 30.Rxf6 Nf7 31.cxb5 Bxe4 32.Kg1 Bf5 33.Qd2 Ne4 34.Rxe4 Bxe4 35.bxa6 Nxh6 36.Qxh6 Rf8 37.Rxf8+ Rxf8 38.Qh3 Qxh3 39.gxh3 Kf7 40.b4 Kf6 41.Kf2 Ke5+ 42.Ke3 Bg2 43.Bf3 Bxf3 44.Nxf3+ Kd5 45.Ng5 Re8+ 46.Kd3 Kc6 47.Nf7 Kd5 
  +/-  (0.78)   Depth: 26/41   00:00:18  225MN, tb=2
[...]
27...Bxd5 28.cxd5 Qd7 29.b3 Nf7 30.Bg4 Qb7 31.Be6 b5 32.Qf3 Nxe6 33.Nxe6 bxa4 34.bxa4 Rc8 35.Bf4 Qd7 36.Qh3 Ne5 37.Bxe5 dxe5 38.Qb3 f5 39.Rh6 fxe4 40.Qb4 Qf7 41.Qe1 Bf6 42.Qxe4 Rc3 43.Qg4 Kh8 
  +/-  (0.82)   Depth: 29/49   00:02:30  1884MN, tb=36
[...]
27...Qd7 28.b3 Ne6 29.Nxe6 Rxe6 30.Qd4 Bxd5 31.Qxd5 Ra7 32.Bd2 Kh8 33.Rhf4 Re8 34.Bc3 Qe6 35.Qd2 Rf7 36.R4f2 Ra7 37.Kg1 Rd7 38.Rd1 Kg7 39.Rff1 Bc7 40.Rf4 Rf7 41.Rdf1 Kg8 42.Qd5 Bd8 43.Qd1 Rd7 44.Qd2 Rf7 45.c5 dxc5 46.Bxa6 Kg7 47.Bxe5 Qxe5 48.Bc4 Ra7 49.Rh4 
  +/-  (0.80)   Depth: 43/50   00:40:40  31133MN, tb=23031

After 27...Bxd5 White's advantage is closer to the full pawn still.

[d]r2br1k1/5q1p/pp1p1ppB/2nbn3/P1PNP2R/4Q3/1P2B1PP/5R1K w - - 0 28

Code: Select all

Analysis by Stockfish 150516 64 POPCNT RCEC:

28.cxd5 Qd7 29.b3 f5 30.Rhf4 Nxe4 31.Nxf5 gxf5 32.Rxf5 Nf6 33.Qg5+ Ng6 34.Bd3 Qf7 35.h4 Ne4 36.Qg4 Nf6 37.Rxf6 Bxf6 38.h5 Qe7 39.hxg6 Bg7 40.Bf4 Rf8 41.Bf5 Rxf5 42.Qxf5 Qh4+ 43.Bh2 Kh8 44.Qd7 Rd8 45.Qc7 Be5 46.Qxh7+ Qxh7 47.gxh7 Kxh7 48.Re1 Bxh2 49.Kxh2 Kg6 50.Re6+ Kf5 51.Kg1 Kf4 52.Kf2 a5 53.Ke2 Kg3 54.Kd3 Kxg2 55.Kc4 Rc8+ 56.Kb5 Rc5+ 57.Kxb6 Rxd5 58.Kc6 Rd3 59.Rxd6 
  +/-  (0.98)   Depth: 40/80   00:35:31  27573MN, tb=102146

Improvements should be sought earlier.

Black 27... Nxa4 seems a pretty major mistake of Komodo. 27... Ne6 seems the best after long Multi-PV = 3 analysis, and the advantage of White seems not so decisive afterwards (+0.74):
SF

Code: Select all

43/84  160:05 +0.74    2.Nxe6 Rxe6 3.Rhf4 Bxd5 4.cxd5 Re8 
                       5.Bg5 Rf8 6.h3 Qd7 7.Bxf6 Rxf6 
                       8.Rxf6 Bxf6 9.Rxf6 Qd8 10.Rf4 b5 
                       11.axb5 axb5 12.b4 Qb8 13.Kh2 Kg7 
                       14.Rf2 Qa7 15.Qg3 (42.408.617.905) 4414 

44/84  172:34 +0.81++  2.Nxe6 (45.972.459.466) 4439 

44/84  185:06 +0.74--  2.Nxe6 Rxe6 (49.457.888.349) 4453 

[tpoppins]

... yet going deeper still shows that 27...Ne6 is hardly better than 27...Qd7 and 27...Bxd5

[d]r2br1k1/1b3q1p/pp1pnppB/3Nn3/P1PNP2R/4Q3/1P2B1PP/5R1K w - - 0 28

Code: Select all

Analysis by Stockfish 150516 64 POPCNT RCEC:

[...]
28.Nxe6 Rxe6 29.Rhf4 Bxd5 30.cxd5 Re8 31.Bg5 Rf8 32.h3 Qd7 33.Bxf6 Bxf6 34.Rxf6 Rxf6 35.Rxf6 Qd8 36.Rf4 b5 37.axb5 axb5 38.b4 Qb8 39.Qc3 Kg7 40.Qd2 Ra1+ 41.Rf1 Rxf1+ 42.Bxf1 Qb6 43.Kh2 Kg8 44.Kg3 h5 45.Kh2 Kh7 46.Qc1 Kg7 47.Qc3 Kf7 48.Qd2 Kg8 49.Kh1 Kg7 50.Qc3 Kh7 51.Qe1 Kg8 52.Qh4 Kf7 53.Qf4+ Kg7 54.Qd2 Kg8 
  +/-  (0.78)   Depth: 44/65   00:37:39  31920MN, tb=32142
28.Nxe6 Rxe6 29.Rhf4 Bxd5 30.cxd5 Re8 31.h3 Qb7 32.Bg4 Nxg4 33.Rxg4 Qd7 34.Qg3 Rc8 35.Bd2 Rf8 36.Bc3 Rf7 37.Kg1 Be7 38.Rgf4 Rcf8 39.h4 f5 40.h5 g5 41.exf5 Rxf5 42.Rxf5 Rxf5 43.Rxf5 Qxf5 44.Qe3 Bf8 45.Qxb6 Qb1+ 46.Kh2 Qd1 47.Qd4 Qxh5+ 48.Kg3 Qg6 49.b4 Bg7 50.Qxg7+ Qxg7 51.Bxg7 Kxg7 52.b5 axb5 53.axb5 
  +/-  (0.87)   Depth: 45/69   01:13:48  61402MN, tb=114575
28.Nxe6 Rxe6 29.Rhf4 Bxd5 30.cxd5 Re8 31.h3 b5 32.axb5 Qa7 33.Qxa7 Rxa7 34.R4f2 a5 35.Rc1 Ra8 36.Bd2 Nd7 37.Rc6 Nc5 38.Bf4 Nxe4 39.Rf1 f5 40.Bd3 Rb8 41.Bxd6 Nxd6 42.Rxd6 Kf7 43.Rc6 Re3 44.Bc4 Rb6 45.b3 Ke8 46.Rd1 Rb8 47.Kh2 Kd7 48.Kg1 Be7 49.Ra1 Bd8 50.Kf1 Bc7 51.Kf2 Rc3 52.Kg1 Bb6+ 53.Kh1 Re3 54.Rf1 Ke8 55.Kh2 Bd4 
  +/-  (0.80)   Depth: 46/69   01:53:07  94499MN, tb=224663
28.Nxe6 Rxe6 29.Rhf4 Bxd5 30.cxd5 Re8 31.h3 b5 32.axb5 Qa7 33.Qxa7 Rxa7 34.R4f2 a5 35.Rc1 Ra8 36.Bd2 Nd7 37.Rc6 Nc5 38.Bf3 Rb8 39.Rxd6 Nxe4 40.Bxe4 Rxe4 41.Bc3 Re8 42.Rf1 f5 43.Rd1 Kf7 44.g4 fxg4 45.Rf1+ Kg8 46.hxg4 Re4 47.Kg2 a4 48.Kf3 Re8 49.Rd7 Re7 50.Rxe7 Bxe7 51.Ra1 Rxb5 52.Ke4 a3 53.bxa3 Rb3 54.Bd4 Rg3 55.Be5 Rxg4+ 56.Kf3 h5 57.d6 
  +/-  (0.87)   Depth: 47/89   05:33:46  283259MN, tb=1037053
28.Nxe6 Rxe6 29.Rhf4 Bxd5 30.cxd5 Re8 31.h3 b5 32.axb5 Qa7 33.Qxa7 Rxa7 34.R4f2 a5 35.Rc1 Ra8 36.Bd2 Nd7 37.Rc6 Nc5 38.Bf3 Rb8 39.Rxd6 Nxe4 40.Bxe4 Rxe4 41.Bc3 Re8 42.Rf1 f5 43.Rd1 Kf7 44.g4 fxg4 45.Rf1+ Kg8 46.hxg4 Re4 47.Kg2 a4 48.Kh1 Re3 49.Ra6 Rxb5 50.Rd1 Rb7 51.Rxa4 Rd7 52.Ra8 Re8 53.b4 Rf8 54.Rc8 Bg5 55.Rxf8+ Kxf8 56.Kg2 Ke7 57.b5 Kd6 58.Bb4+ Kc7 
  +/-  (0.86)   Depth: 48/89   06:09:47  315190MN, tb=1326737
28.Nxe6 Rxe6 29.Rhf4 Bxd5 30.cxd5 Re8 31.h3 b5 32.axb5 Qa7 33.Qxa7 Rxa7 34.R4f2 a5 35.Rc1 Ra8 36.Bd2 Rb8 37.g4 Nf7 38.Bd3 Ne5 39.Bf1 Kg7 40.Bf4 Bb6 41.Rfc2 a4 42.Kg2 Bc5 43.Ra1 Ra8 44.Rcc1 Ra7 45.Ra2 Nd7 46.b4 Bxb4 47.Rc4 Bc5 48.Rcxa4 Rxa4 49.Rxa4 Nb6 50.Ra6 Rxe4 51.Bxd6 Bxd6 52.Rxb6 Be5 53.Rc6 Kf7 54.Bc4 Ke7 55.Kf3 f5 56.Re6+ Kd7 57.b6 
  +/-  (0.91)   Depth: 49/89   06:25:20  328637MN, tb=1397323

(all fail-highs/lows edited out for the sake of concise presentation)

Whatever Black might play on move 27 he would still stand badly. That was the result of not a single mistake but a series of inferior moves - 17...g6, 18...Bf6, 20...Re8 and 21...Bd8 - that lead to a weakening of the black king's position and left the black pieces in a disorganized, uncoordinated state. 27...Nxa4 was just a blunder that gave White a won game.