The first recurring theme is that my opponent makes some very reasonable-looking moves that don't in fact work in the position; examples include on move 8, move 10, and move 28. How often do we make a move relatively quickly in a position, because it looks reasonable or perfectly normal, without actually working it out? This can especially be a problem in the opening phase, when we reach a similar (but not exact) position to one we're familiar with, and make a move on autopilot that turns out badly.
The second theme is that of blind spots. Here, for me it is the beautiful-looking Bg2 on the long diagonal, which I nevertheless should have looked to exchange around move 14 for a concrete advantage. A lesser version of this long diagonal blind spot can be found on move 25, when I didn't even consider f3 as a possibility; however, when my opponent makes himself vulnerable on the long diagonal, I eventually find the idea.
[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "ChessAdmin"]
[Black "Class B"]
[Result "1-0"]
[ECO "A26"]
[Annotator "ChessAdmin/Komodo 11.2"]
[PlyCount "103"]
[EventType "simul"]
[EventRounds "6"]
{[%mdl 8192] A26: English Opening vs King's Indian with ...Nc6 and d3} 1. c4
Nf6 2. Nc3 g6 3. g3 Bg7 4. Bg2 O-O 5. Nf3 d6 {my opponent indicates he is
going for a KID formation rather than transposing into, for example, a
Symmetrical English with ...c5} 6. O-O e5 7. d3 Nc6 8. Rb1 Be6 {a large number
of different moves have been tried here by Black. The text move fights
directly for d5, but may prematurely commit and expose the bishop.} 9. Ng5 {
this takes advantage of the opportunity to pressures the Be6 and at the same
time unleash the Bg2.} (9. b4 $5 {is also good, proceeding with the queenside
expansion plan.}) 9... Qd7 10. b4 (10. Nxe6 {is preferred by the engine.} fxe6
{I thought at the time this would help Black, by clearing the f-file for his
rook and strengthening his claim to the d5 square. However, White's queenside
expansion comes first, beating Black's potential central play.} 11. b4 {
and now the combination of the vulnerable Nc6 and b7 pawn becomes awkward for
Black. For example} Nd8 12. b5 c5 (12... d5 $2 13. cxd5 exd5 14. Nxd5 Nxd5 15.
Qb3 {now the Nd5 cannot escape the pin.} c6 16. bxc6 bxc6 17. e4 $18) 13. Qb3
$16 {with the simple plan of pushing the a-pawn.}) 10... Rab8 {a
reasonable-looking move, with the rook protecting b7 and getting off the long
diagonal, but White can rapidly realize an advantage.} (10... Bf5 $5 $14) 11.
Nxe6 $16 Qxe6 12. Bg5 {done with the idea of getting the dark-square bishop
off the first rank and potentially exchanging it for the Nf6, which is a key
defender of d5.} (12. b5 {would instead force the issue for Black, for example}
Nd4 13. e3 Nf5 {and now White has a pleasant choice of moves.} 14. Nd5 (14. Qa4
$5)) 12... h6 {I am perfectly happy to exchange.} 13. Bxf6 Qxf6 14. Nd5 {
a nice square for the knight, but I should have been looking for more forcing
opportunities on the queenside, which is vulnerable.} (14. Qa4 {this or
immediately capturing on c6 are both good. I had a bit of a blind spot here,
ignoring the concrete benefits of exchanging off the Bg2. It is beautifully
positioned on the long diagonal, but capture possibilities should not be
ignored as a result.} Nd4 15. Qxa7 c6 16. b5 $16) 14... Qd8 15. b5 Nd4 16. e3 {
I've learned the hard way not to leave a centralized Black knight on d4, so
immediately kick it. Without a dark-square bishop, having a pawn on e3 also
does not cramp my pieces.} Ne6 17. a4 f5 {my opponent clearly wants to create
some kingside counterplay, but the center of gravity is still on the queenside.
} 18. Nb4 Kh7 {ignoring the coming threat.} 19. a5 {now Black's main problem
is that the b-pawn cannot advance to b6 without giving up the c6 square to my
knight.} Qd7 20. a6 bxa6 (20... b6 21. Nc6 Ra8 22. Bd5 $16 {and White's minor
pieces are dominant.}) 21. Nxa6 {now Black's a-pawn is weak and isolated and
my minor pieces are much more effective than Black's.} Rbd8 22. Ra1 (22. Bd5 {
played first would have enhanced the bishop's domination and avoided Black's
next move.} Ng5 23. h4 Ne6 24. Ra1 $18) 22... e4 23. d4 {the natural move,
blocking Black's Bg7 and enhancing my central pawn structure.} Ra8 24. Nb4 (24.
h4 $5 {is Komodo's idea, more or less forcing Black to fix the pawn structure
on the kingside and then White has plenty of time to maneuver on the queenside.
} h5 25. Ra2 $18) 24... Rfb8 $6 $18 (24... a5 {is the best try here, although
it's not at all obvious, as it seems White can just take en passant on a6.
However} 25. bxa6 $6 (25. Nc6 $16 {is best}) 25... c5 {and now Black has
significant counterplay.}) 25. Ra2 (25. f3 {played immediately would be
beneficial, as e4 is now vulnerable.} a5 26. Na6 $18) (25. Ra6 $5 {is a better
version of the text move's idea of doubling rooks on the a-file. Black's
a-pawn is blocked and the rook exerts lateral pressure along the 6th rank.})
25... Rb7 $2 {now with Black lining both his rooks up on the long diagonal as
targets, I find the correct move.} 26. f3 $18 Ng5 {the best try.} 27. fxe4 Nxe4
28. Qd3 Qe8 $2 {another reasonable-looking move that does not work.} 29. Rf4 (
29. g4 {is the quicker path to victory, immediately undermining the Ne4.} c6
30. gxf5 gxf5 31. Rxf5 $18) 29... c5 30. Bxe4 fxe4 31. Rxe4 {at this point the
game largely plays itself for White, although Black fights on.} Re7 32. Rxe7
Qxe7 33. dxc5 {following the rule of simplification when ahead.} dxc5 34. Nc6
Qc7 35. Qd5 {centralizing the queen and setting up a discovered attack threat
against the Ra8.} Bf8 36. Rf2 {threatening a fork on f7.} Kg7 37. Ne7 {forcing
material loss.} Qxe7 38. Qxa8 h5 39. Qxf8+ {and now with a 100 percent won K+P
endgame, I simplify down. Black cannot protect his weak a- and c-pawns and
also prevent the e-pawn from queening.} Qxf8 40. Rxf8 Kxf8 41. Kf2 Ke7 42. Kf3
Ke6 43. Ke4 (43. Kf4 Kf6 44. h3 Ke6 45. e4 Kd6 46. e5+ Ke6 47. Ke4 g5 48. h4
gxh4 49. gxh4 Ke7 50. Kf5 Kd8 51. e6 Ke7 52. Ke5 Kd8 53. Kf6 Kc7 54. e7 Kd7 55.
Kf7 Kc7 56. e8=Q Kb6 57. Qd8+ Kb7 58. Kf6 a6 59. b6 a5 60. Qc7+ Ka6 61. Qa7#)
43... g5 {this is just a distraction, and now the g-pawn will also become a
target.} 44. h3 h4 45. g4 {maintaining the opposition for White and forcing
Black's king to give way.} Kd6 46. Kf5 a5 47. bxa6 Kc7 48. Ke5 {keeping the
win simple.} Kb6 49. Kd5 Kxa6 50. Kxc5 (50. e4 Kb6 51. e5 Kb7 52. Kxc5 Kc7 53.
e6 Kc8 54. Kd6 Kd8 55. c5 Ke8 56. c6 Kf8 57. e7+ Kg7 58. c7 Kh7 59. c8=Q Kg7
60. e8=Q Kh7 61. Qh5+ Kg7 62. Qch8#) 50... Kb7 51. e4 Kc7 52. Kd5 {and my
opponent resigned.} (52. Kd5 Kd7 53. e5 Ke7 54. e6 Ke8 55. Kd6 Kd8 56. e7+ Ke8
57. c5 Kf7 58. c6 Ke8 59. c7 Kf7 60. c8=Q Kg7 61. Qf5 Kg8 62. e8=Q+ Kg7 63.
Qef8#) 1-0