1. e4 c5 2. Nf3 Nc6 This is the Classical Sicilian Defense, known for it's straightforward development. The other main theme in the Sicilian is
2... d6 with it's own class of theories. The Sicilian Defense is one of the best openings, but is also one of the deepest and most complicated of all opening, with volumes devoted to it's study.
3. d4 cxd4 4. Nxd4 g6 This is characteristic of the Accelerated Dragon variation of the Sicilian. Traditionally, it is more common in the 2... d6 lines, and usually after ... Nf6, but this move order is gaining popularity at all levels of play.
5. Bc4 Most common for White here is
5. Nc3
or
5. c4 the famous Maroczy Bind.
The move played seems perfectly acceptable, but I'm not up on the theory of this variation, so I'm, not qualified to comment more on it at this time.
5... Qa5+ An interesting continuation. The move does create some problems for White, as the most obvious replies fail to tactical shots. Nor example, if 5, Bd2? or 5. Nc3 then 5... Qc5, or if 5. c3 White's development is inhibited, although that is the best reply. On the other hand, the Black queen has been brought out too early, and White may be able to profit by this, attacking it to further his development. Alternative for Black at this point all transpose into more studied and conventional lines.
6. Bd2? Qc5 7. Nxc6 Qxc4 8. Na5 Qxe4+ 9. Kf1 As ugly as it is, this is White's best move. Black has a nice advantage, owing to White's misstep at move 6. White is going to be on the defensive for a long time, with a poorly placed knight and a blocked in rook, while Black's plan will be to develop while attacking the enemy kingside, eventually pushing his pawns into a long chain to exploit his material edge.
9... Nf6 9... Bg7 is slightly better, as it superficially threatens the White rook. The game might then go 10. Nc3 Qf5 threatening the other knight 11. Nb3 b6
In fact, developing Black's light squared bishop is such a good idea it can also be done right away, as in
9... b6 10. Nb3 Bb7 11. f3 Ba6+ 12. Kg1 with an embarrassing kingside for White.
10. Nc3 Qe5 Not bad, but
10... Qf5 is better since the queen cannot be attacked so easily on that square.
11. Nc4 Qb8? This move completely gives away Black's positional superiority, making his queenside even worse than White's kingside, abandoning the center, and so restricts the queens movements that she may become trapped.
12. Qf3 Much better is 12. Bg5 Bg7 13. Bxf6 Bxf6 14. Nd5 Bg7 15. Qe1 e6 16. Qb4! and Black is forced to resort to 16... Bf8 after which 17. Qc3 (17. Qe1)
(17. Nf6+)
are all playable.
12... Bg7 13. Re1 d6 Protecting the queen for now but making her rehabilitation all the more difficult.
14. Bf4 14. Bh6! and if 14... Bxh6 15. Qxf6 O-O 16. Qxe7 This is possible because White controls the center and Black's development lags.
14... Be6 This move is necessary and isn't so bad, since the dark squared bishop is fianchettoed. With every piece gotten off the back rank, Black's game improves. But it is necessary for Black to get the queen off of b8.
15. Ne3 O-O 16. Ned5 Nxd5 17. Nxd5 Bxd5 18. Qxd5 e5? I prefer
18... Qc7 on principal. As mentioned above, developing the queen is critical for herself and for the queen rook. Also, the move played makes the d pawn dangerously backwards and exposed on a file White can readily control.
19. Bg3 The bishop has too little scope from this square. Redeployment to the queenside would have been preferable.
19... Qc7 20. c3 Rac8 21. Rd1 Rfd8 22. Ke2 Qc5 If Black wanted to trade off queens, which isn't a bad idea,
22... Qc4+
was the way to do it.
23. f4? The timing of this moves makes no sense. White just placed his king onto a more vulnerable square, presumably to develop the king's rook to the e file, a good plan which he should follow through on. Until that's been done, White is only asking for trouble by opening up lines.
23... exf4 Now that Black has been given attacking chances, the queen becomes a valuable asset as an attacker, and should be taken off the block with
23... Qb6 threatening a pawn with check on b2. With the move played, it's now better for White to exchange queens, but he doesn't do it.
24. Bxf4 Re8+ 25. Kf3 Dangerous, but the only way to preserve hope of getting the other rook into the game.
25... Qxd5+? A significant strategic error. Granted, the White queen is useful in defense, but the Black queen is useful in the attack. But the real consequence is that Black makes the d pawn permanently isolated, and that extra pawn is a major advantage Black has had. Unless he envisions tactics that will lead to a win in short order, the pawn situation should be preserved or even improved. The way to do that is
25... Be5
26. Rxd5 Be5 27. Re1 27. Rhd1 was better to maintain pressure on the isolated d pawn and to keep control of the second rank so that intruders can be challenged.
27... Kf8 Better is 27... Bxf4 28. Rxe8+ Rxe8 29. Kxf4 Re2
As played, the game should draw as an even rook and pawn ending. The asymmetry of pawn placement is not enough to give either side an appreciable edge.
28. Bxe5 dxe5 29. Rexe5 Rxe5 30. Rxe5 f6 31. Rd5 Ke7 32. Ke4 Ke6 33. g4 Rc4+ 34. Rd4 f5+ I don't like the splitting of the kingside pawns for Black, as that puts them both at risk of capture, and makes their progress to the back rank difficult.
35. gxf5+ gxf5+ 36. Ke3 Rxd4 37. cxd4 I don't like the splitting of the White pawns either, for the same reasons.
37... Kd5 Black would do better to advance the queenside pawns first, to gain time should the ending turn into a race on opposite wings. In fact, the game is now lost for Black, though it is very difficult to count out over the board. Perhaps the best move here is a draw offer.
38. h4 h5? Although Black cannot save his game any longer, this move only makes it easier for White. Rather than blocking the h pawn, it gives the White king a shorter trip to capturing it. Black gives white more chances for error by advancing the queenside pawns and making it seem both sides have chances, in which case a draw offer is more likely to be accepted.
39. Kf4 Ke6 40. d5+ Kxd5 41. Kxf5 a5 The right idea, but much too late. White does best to simply ignore it, but it makes little difference, since Black is so many tempo behind.
42. a4 b6 43. Kg5 Ke6 44. Kxh5 Kf7 45. Kg5 Kg7 46. h5 Kh7 47. h6 Kg8 48. Kg6 Kh8 49. h7 b5 Ouch, but it's forced.
50. axb5 a4 At this point, the score has stopped, so it's hard to tell if Black now resigned, lost on time, or if the game continued with 50. axb5 a4 51. b6 a3 52. b7 axb2 53. 8=Q#. But in any case there was no real hope of a stalemate as white can simply abandon the h pawn and have two connected passers on the other wing.
1-0
1. e4 d6 2. d4 Nf6 3. Nc3 g6 4. Nf3 Bg7 5. Be2 O-O 6. O-O c6 7. h3 b5 This has been a Classical Variation of the Pirc Defense until this point. The book move is 7... Qc7 after which White has a few options.
8. a3 Nbd7 9. e5 dxe5 10. dxe5 Ne8 11. e6 White sacrifices a pawn to disrupt Black's position. While the idea is good, it's execution is premature. White should complete his development, possibly doubling rooks or rook and queen in the center, before releasing the tension. Black should not be able to marshal his defensive forces as quickly as White can build for the attack.
11... fxe6 12. Ng5 Nc7 13. Bg4 Nf6 14. Be3 h6 Black should trade off the queens on d1, possibly the bishop for knight on g4 if White doesn't move the bishop in retaking the queen, and deploy a knight to d5 to either improve his own pawn structure or damage White's in compensation. Then the extra pawn he has will become a valuable asset.
15. Nge4 Nxe4 16. Nxe4 h5 16... Bxb2? 17. Bxh6 Bxa1 18. Qxa1! Rf7 19. Rd1 with good play.
17. Bf3 Qxd1 18. Raxd1 Bxb2 Black is now two pawns ahead, but still lags in development and has a pawn structure somewhat worse than White's, but overall has much the better game.
19. Rd3 Bg7 20. Bc5 Nd5 21. Ng5 b4 The pawn in momentarily immune thanks to the threat of ... Ba6 skewering the rooks.
22. Re1 a5 23. g3 White avoids the trap 23. Nxe6 Bxe6 24. Rxe6 Nf4 but now such a maneuver is possible.
23... Bc3 23... Ba6 is also worth consideration here, though it is very complicated as White can unbalance the position by giving up the rook to take other material. Perhaps Black was hoping White would place the attacked rook on d1, after which Ba6 is even more effective.
24. Re4 bxa3 Better here are moves such as 24... Rf6
or
24... Rf5
or
24... Ba6
or
24... e5 to finally activate the light squared bishop.
The move played, while not bad in itself, simplifies White's defensive tasks.
25. Bxa3 Ba6 26. Rd1 Nb4? This knight is the keystone of Black's position, and White should have been considering sacrificing to remove it from it's post. For black to take it away voluntarily gives up all his advantage.
27. Rxe6 Bb5 27... Bf6
28. Rxg6+ Kh8 29. Rd7 Rae8? Black is suddenly very concerned with staving off mating threats, but the proper way to handle this is by 29... Rf6 Unfortunately, in the last five moves, Black's game went from probably won to almost certainly lost.
30. Bxh5 c5 31. Rd1 31. Rh6+ Kg8 32. Bxe8 Rxe8 33. Rg6+ Kh8 34. Bxb4 Bxb4 35. Ra7 is a fairly simple win.
31... Rf6? The rook on e8 should move.
32. Rxf6 exf6 33. Bxe8 Bxe8 34. Ne4 Ba4 35. Nxc3 Bxc2 36. Rd2 Bg6 37. Bxb4 The knight is less of a potential threat than connected passed pawns can be. This exchange only gives White opportunities to suffer serious consequences for small errors.
37... axb4 38. Nd1 c4 39. Rd8+ Kg7 40. Rc8 c3 41. Nxc3 The best and simplest way to handle the ending.
41... bxc3 42. Rxc3 Kh7 43. Rc6 Kg7 44. f4 Bf5 45. g4 1-0