In this case, after an up-and-down opening (first up, then down), I blunder the exchange - although if you win in the end, you can call it an "unintentional exchange sacrifice". After the "sacrifice" I do fight well for compensation, while in contrast my opponent plays passively and focuses on attempting to trade down material, without much else in terms of a plan. I spot a possible tactic after my opponent weakens his kingside with 27...g6?! and eventually get the chance to execute it, leading to a breakthrough and a win. (By coincidence - or perhaps not - this matches up nicely with ideas in the recent "importance of sequencing" post).
While reviewing my initial notes in the database, I was struck by how the final result colored my outlook on the entire game. My opening play was initially fine but then got significantly weaker as I approached the middlegame, which is a recurring pattern that I've identified (so will now fix, as in Third Time's the Charm). Specifically, one of my main recurring errors has been neglecting development and allowing my opponent to restrict my pieces, which always brings problems with it. I should have been harsher (or more realistic) during my earlier evaluation and recognized that the narrative of triumph after the "unintentional sacrifice" was due less to my abilities - although I did find some correct ideas - rather than my opponent's passivity and creation of unnecessary weaknesses.
[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "ChessAdmin"]
[Black "Class C"]
[Result "1-0"]
[ECO "A11"]
[Annotator "ChessAdmin/Komodo 9.3"]
[PlyCount "75"]
[EventDate "2016.??.??"]
1. c4 Nf6 2. Nc3 e6 3. Nf3 d5 4. e3 c6 5. b3 Bb4 {this was a little surprising,
I felt that ...Bd6 would be more in keeping with Black's Semi-Slav type setup.}
6. Bb2 O-O 7. Qc2 Qd6 {this seemed like a premature development of the queen,
as well as restricting the Bb4's retreat squares. We are now out of the
database.} 8. a3 {the obvious reaction, inconveniencing the bishop.} Ba5 9. b4
{continuing with the theme of pushing back Black's pieces and gaining space on
the queenside. Perhaps not most effective, however. The bishop on a5 is not
doing much and represents a waste of time for Black, while the new square it
goes to is more useful.} (9. d4 $5 {would get space in the center and make a
the follow-on Bd3 development logical.}) 9... Bc7 10. c5 {this does nothing
for my development and leaves Black's d-pawn looking stronger.} (10. Be2 dxc4
11. Bxc4 $14) 10... Qe7 $11 11. Be2 {again, d4 is logical but would have the
disadvantage of shutting in the Bb2.} b6 {challenging the pawn chain at its
top.} 12. cxb6 axb6 13. O-O Bb7 {Black continues with a rather slow
development plan.} 14. Rfd1 Nbd7 {although I felt that Black had not played
the opening particularly well, at this point his development is fine and a bit
better coordinated than mine. He is certainly better positioned in the center
for space. Komodo gives a slight edge to Black.} 15. d3 {in the expectation
that the following sequence would occur.} e5 16. e4 d4 17. Nb1 c5 $6 {this
seems like an obvious move at the Class level, to advance and support the d4
pawn, but with Black having gained space and restricted my pieces, this just
allows me to get some breathing space on the queenside.} (17... b5 $5 {would
lock things up to Black's advantage.}) 18. bxc5 $6 (18. Nbd2 {would help with
my neglected piece development.}) 18... bxc5 {this is what I had expected.} (
18... Nxc5 $1 {and now Black will dominate the queenside, likely winning the
a-pawn and causing major problems once his bishops get further into play from
d6 and c6.}) 19. Nbd2 Bc6 {here I failed to ask the question in my thinking
process, what did my opponent's move change about the position? What new CCT
does he now have available?} 20. Nc4 $2 {this leads to an unintentional
exchange sacrifice. I spotted Black's skewer tactic immediately *after* moving.
I therefore played the next couple of moves rapidly and with confidence, since
there was nothing else to be done.} (20. Rdc1) (20. a4) 20... Ba4 $17 21. Qd2
Bxd1 22. Bxd1 {a key part of the sequence for White, capturing with the bishop
rather than the queen. The bishop will be repositioned to a much better square,
serving as partial compensation for the sacrifice.} Nb6 {normally it's a good
idea to simplify with piece exchanges in order to magnify a material advantage,
and this was presumably my opponent's main idea here. However, this benefits
me by accelerating the activation of my light-square bishop.} (22... Rfb8) 23.
Nxb6 Bxb6 24. Qg5 {I felt this was necessary to develop counterplay. The queen
has to be activated and has a relatively open field in front of the Black king.
The pin on the Nf6 will also lose Black some time.} Rfe8 {unpinning the Nf6.}
25. Bb3 {While Black is still comfortably winning on objective measures, this
bishop now becomes a monster on the a2-g8 diagonal and its pinning of the f7
pawn will eventually be the decisive factor in the game.} Bc7 {clearing the
b-file for one of Black's rooks and reinforcing e5. However, a Black rook
never ends up on the b-file.} 26. Bc4 {anticipating future possible pressure
down the b-file.} Nd7 {offering a queen trade.} 27. Qh5 {naturally I avoid
trading queens and maintain some pressure on Black's kingside, adding h7 as a
target and attacking f7 again. Ng5 now becomes a potential threat.} g6 $6 {
unnecessarily weakening the squares in front of the Black king.} (27... Nf6 {
is what I was expecting.} 28. Qg5 {and we try again with the position.}) (27...
Rf8 {is the engine's choice, but this sort of defensive move can be
psychologically hard to play, especially since the rook had just recently
moved away from f8.}) 28. Qh6 Qf8 {this apparently was the idea behind the
previous move, but this ends up placing Black's queen on a much more awkward
square.} 29. Qh3 Nf6 {in contrast with the previous situation, now the Nf6 is
not protected.} 30. Bc1 $15 {bringing another piece around to exert pressure
and materially improving the evaluation for White, as previously the
dark-square bishop was locked out of the game. Part of my compensation for
being down an exchange is that I am able to use both bishops and the knight
effectively to attack the kingside, along with the queen, while Black has only
the queen and knight defending the kingside.} h5 31. Bg5 $6 {wrong piece. The
bishop is doing fine on the c1-h6 diagonal where it is, while the knight could
do better on g5. Attacking the Nf6 is not much of a threat in reality,
although it does prompt my opponent to play an awkward follow-up move.} (31.
Ng5 {would target f7 and increase the pressure.} Re7 32. Qh4 $15) 31... Bd8 (
31... Qd6 $17 {is much better, getting the queen to a more effective square.})
32. Qg3 {leaving the diagonal and shifting the queen's target to the now
underprotected e5 pawn.} Nd7 $2 {missing the following tactic, one which I had
spotted as a possibility after 27...g6, based on the pin of the f7 pawn. I
believe my opponent was still focused on a general plan of trading down
material.} (32... Qd6) 33. Bxd8 $18 Raxd8 34. Qxg6+ Kh8 (34... Qg7 35. Bxf7+
Kf8 36. Bxe8 Rxe8 37. Qxh5 $18) 35. Qxh5+ Kg7 36. Qg4+ {I thought for a while
before making this move. I wanted to bring another piece (the Nf3) into the
attack by leaving the g5 square open for it.} Kh8 37. Ng5 {now the combination
of mate threats plus the attack on f7 decide the game.} Nb6 38. Qh5+ 1-0