Tactics: A good Knight for a bad King?

28...Qf5 saves the piece because if White takes the N there is a pretty mate: 29. bxc5 Qxf2+ 30.Kh3 Qf5+ (only move) 31. g4 Qf1+ 32. Ng2 Rf3+ 33. exf3 Qxf3+ 34. Kh4 Bf6+ with mate next.

However, 28...Qf5 is not the best move, because after 29.f4! the position is close to equal, though computers rate Black as a bit better after 29... g5. 

28... Qd7 looks like a blunder, since White can play 29.Rxc5 and it seems that White is winning a piece. But after 29... Qf7 the Rc5 is hanging and White's K is in peril, e.g.: 30.Rc2 Qxf2+ 31.Kh3 Rf5-+.

In fact 28... Qd7 is not a good move, but for a different reason: after 29.Qxd7 Nxd7 30.Rd1! White wins a pawn. 

28...Rxf2!! is the best move of the three, but it's complicated.

Obviously, taking the Rook loses: 29. Kxf2? Nd3+ and Black wins the Qb5. So the real question is: what should Black play after 29. Kg1?

28...Rxf2 29. Kg1

The game ended like this:

29... Rxe2? 30. Qxe2 d3 31. Nxd3! Nxd3 32. Rc7 Nxb2 33. Qxb2 Qd1+ 34. Kg2 Qf3+ 35. Kg1 Qd1+ 36. Kg2 Qf3+ 1/2-1/2

Alex Danilov - Jacob Krolczyk
RA Winter Open U1900
2014.01.18

But Black had two better continuations... 29... Qf5 and 29... Qh5:

29... Qf5 (Threatens a mating attack with ...Rf1.) 

30. Ng2 (30. bxc5? Rf1+ 31. Kg2 Qf2+ 32. Kh3 Rg1 (threat: ...Qf5) 33. cxb6 Qf1+ -+) 

30... Na4

(30... e3 31. bxc5 Qh3 32. Qc6 Rxe2 33. Bxd4 Bxd4 34. cxb6 and it's anybody's game.)

31. Qxa4 Rxe2 32. Rf1 Qh3 33.Rf2 Rxf2 34.Kxf2 e3+ Black's advanced pawns will cost White both his minor pieces.

 29... Qh5 wins too: Black threatens mate on h2, but also eyes the pawn on e2.

30. Kxf2 (30. Ng2? Rxe2 -+) 30... Qxh2+ 31. Ng2 e3+ 32. Kf3 Qh5+ 33. g4 Qh3+ 34. Kf4 h5 and White is getting mated.