The final position makes a pretty picture:
Topalov, playing black, whipped out a novelty in the well-trodden Meran Variation of the Semi-Slav. He managed to produce an objectively equal but materially imbalanced endgame where he had two knights against Kramnik’s rook and pawn. This is just the sort of position Topalov loves, and he managed to pounce on some inaccurate moves by Kramnik.
In the diagrammed position, white can’t avoid mate. Black has just played 52. … Rb2-f2. White gets mated after 53. Kg1 Rxg2+ 54. Kf1 Rf2+ 55. Ke1 Nd3+ 56. Kd1 Rd2 mate. Other moves for white just lead to faster mates. The black knights have set up shop on commanding posts, and the white rooks can only cower before them.
It was a brilliantly played game by Topalov and his first real win. Officially the match is now tied, though I suspect every chess fan still regards Kramnik as being up by one. For Topalov to win such a game as black is a major accomplishment.
Four games remain. I’m seriously rooting for Kramnik now. If he manages to win the match outright, even with the forfeit, that all of Topalov’s shenanigans will have to naught, and Kramnik will be the deserving winner. But if the match ends in a tie becuase of Kramnk’s forfeit in game five, or if Topalov wins only because of the forfeit, then the match will have failed to produce a real champion. And that would be a tragedy for chess.