ok, I'm proud of this one, this is also my first sac in a game. of course this is not the only reason I'm strarting this thread, I think the game is pretty instructive and interesting. Game 3372268
1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e5 6. Ndb5 a6 7. Nd6+ Bxd6 8.Qxd6 Qe7 9. Qxe7+ Nxe7 10. Bg5 b5 11. O-O-O h6 12. Bxf6 gxf6 13. a3 Bb7 14. f3 Rd8 15. b4 d6 16. Bxb5+ axb5 17. Nxb5 Nc8 18. c4 O-O 19. Kb2 Rd7 20. Kb3 Bc6 21. Ra1 Bxb5 22. cxb5 Nb6 23. Rhc1 Rc8 24. Rxc8+ Nxc8 25. Rc1 Rd8 26. a4 Kf8 27. a5 Ke7 28. Rc7+ Ke8 29. b6 Nxb6 30. axb6 Rb8 31. b7 Kd8 32. Rxf7 h5 33. Kc4
Ke8 34. Rh7 Kd8 35. Kd5 1-0
the sac is 16.Bxb5+. my later analysis with rybka tells me that black is slightly better after the sac, but I got deeper and deeper into variations and almost all came out to be drawish positions, where the defending side (black) had to be very accurate.
white came out of opening with a good middle game with black's mistake 6...a6?, and castling kingside for black was also a serious mistake, he needed the king to defend, because we were actually already into the endgame.
and I think somewhere in the game he needed to try to break through the middle pawns with ...f5, and combining with that, try to get some kingside counterplay with the rook by ..Rg8 (of course castling kingside stopped this chance too).
I don't find any serious mistakes for white except 21.Ra1?, which actually has no point other than just trying to slowly but surely push the a pawn, which was pretty superficial.
at first I decided to try not to give any exchanging chances to my opponent, but later I thought I could win the game very comfortably if the only piece left in the board was a black knight, so I didn't try to prevent 21...Bxb5, and later exchanged the rooks myself.
and about black's giving back material with 29...Nc8xb6, he didn't have any other choice because of the threar of 30.b7, where the knight would be blockade for the black rook and didn't where any place to go.
after 35.Kd5, my opponent resigned because there was no possibility to stop 36.Kxd6 Ke8 37.Rh8+ Kf7 38.Rxb8 and mates very quickly.
I actually made almost no calculations before the sacrifice, but I thought the game would be very interesting, and figured that black didn't have any immediate chances to attack, so I would be able to maintain the connected passed pawns up in black's territory for a long time, and black had to be careful. I also was inspired by the similar sac of Bronstein (which was backed up with stronger analysis of course), where he has thought for 58 minutes !!! kasparov says. here's that game also, I think it's also very interesting:
[White "Bronstein David I"]
[Black "Najdorf Miguel"]
1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Bg5 e6 7. Qf3 Nbd7 8. O-O-O Qc7 9. Qg3 b5 10. Bxb5 axb5 11. Ndxb5 Qb8 12. Nxd6+ Bxd6 13. Qxd6 Qxd6 14. Rxd6 h6 15. Bd2 Bb7 16. f3 O-O 17. b3 Rfc8 18. Kb2 Nc5 19. Be3 e5 20. Rhd1 Ne6 21. Rb6 Bc6 22. Nd5 Bxd5 23. exd5 Nc5 24. Rb5 Nfd7 25. c4 e4 26. Bxc5 Nxc5 27. fxe4 Nxe4 28. d6 Rxa2+ 29. Kxa2 Nc3+ 30. Ka3 Nxd1 31. c5 Nc3 32. Ra5 Nd5 33. c6 Nf6 34. Ra6 Kf8 35. b4 Ke8 36. b5 Nd7 37. Ra7 Rb8 38. Rxd7 Rxb5 39. Ra7 Rb8 40. d7+ Ke7 41. d8=Q+ Kxd8 42. c7+ 1-0