daughtrylp vs CtrlAltDefeat-00

How it swung

The one slip

41...♘xb2+ cost 10.6 pawns. ♖d2# would have held it.

There was mate on the board here. 41...♖d2# is it.

The score

1. 1. d4 d5
2. 2. Nc3 Nf6
3. 3. Bf4 Bf5
4. 4. Nb5 Na6
5. 5. e3 c6
6. 6. Nc3 e6
7. 7. Bd3 Bxd3
8. 8. Qxd3 Nb4
9. 9. Qd2 Bd6
10. 10. Bg3 O-O
11. 11. a3 Na6
12. 12. f4 b5
13. 13. Nge2 c5
14. 14. Bh4 cxd4
15. 15. Nxd4 Nc7
16. 16. h3 Be7
17. 17. O-O-O Nh5
18. 18. Bxe7 Qxe7
19. 19. g4 Ng3
20. 20. Rhg1 Ne4
21. 21. Nxe4 dxe4
22. 22. g5 Rfd8
23. 23. Qe2 f5
24. 24. gxf6 Qxf6
25. 25. Rh1 a6
26. 26. h4 h5
27. 27. Qxh5 g6
28. 28. Qh6 Kf7
29. 29. h5 Rg8
30. 30. Qh7+ Rg7
31. 31. hxg6+ Qxg6
32. 32. Qxg6+ Rxg6
33. 33. Rhg1 Rxg1
34. 34. Rxg1 Nd5
35. 35. Kd2 Rh8
36. 36. Rg2 Rh3
37. 37. c3 Nxe3
38. 38. Re2 Nc4+
39. 39. Kc2 Rh4
40. 40. Rxe4 Rh2+
41. 41. Kd3 Nxb2+
42. 42. Ke3 Nd1+
43. 43. Kd3 Nf2+
44. 44. Ke3 Nxe4
45. 45. Kxe4 Rh3
46. 46. a4 bxa4
47. 47. c4 a3
48. 48. Nc2 Rc3
49. 49. Na1 Rxc4+
50. 50. Kf3 Kf6
51. 51. Kg4 e5
52. 52. Nb3 Rxf4+
53. 53. Kg3 Kf5
54. 54. Nc5 a2
55. 55. Nxa6 a1=Q
56. 56. Nb4 Qa3+
57. 57. Kg2 Qf3+
58. 58. Kh2 Rh4+
59. 59. Kg1 Rh1#