[FEN "7Q/5p1p/1pPr2pk/8/8/3pP2P/2q2PP1/3R1K2 w - - 0 43"]
43. Qf8+ Kg5 {This is now the above position and White played.....} 44. Kg1 {And as incredible as it seems this amazing move wins. The game continued.} 44... Qxd1+ 45. Kh2 Rxc6 46. Qe7+ Kh6 47. Qf8+ Kg5 48. Qxf7 {White is threatening Qf5+ or f4+ which mates Black or forces Black to give up the Queen or Rook. Apparently there is no defence.} 48... Rf6 49. f4+ Kh6 50. Qxf6 Qe2 {Pinning the g-pawn to stop Qf8+ and g4+ mates.} 51. Qf8+ Kh5 52. Qg7 h6 53. Qe5+ {If now g5 as Black then Qe8+ mates.} 53... Kh4 54. Qf6+ Kh5 55. f5 {Threatening Qxg6 mating.} 55... gxf5 56. Qxf5+ Kh4 57. Qg6 {Black resigned there is nothing to stop.....} 57... d2 58. Qxh6+ Qh5 59. g3
Hmmm... is that really the move of the year? AFAICT it's reasonably obvious, not so much because it's obvious that it wins, as that it's obviously the only move which doesn't immediately lose (at least, I, in my patzerishness, can't see any other.)
Now, continuation of the year, that it may well be, because to get from "a rook down but still alive" to "winning", Khismatullin had to pull off a few deft manoeuvres. But that first move? Not the key, I think.