Phew, I got lucky too I actually noticed that motif when I was looking at another line but didn't even consider 30. Rh5+. Glad it still works out

White seems able to get perpetual check in this line. E.g. 32. Kxg4 Nxd2 33. fxg7 Kxg7 34. Rg5

Also White is not forced to trade his rook on move 31, though I guess after 31. ...g6 he'll have nothing to show for it.

Anyway I don't like Qe3 for black for this reason.

OK, so its officially a knight ... the rest of the sink comes with the swindle in mind ...
28.Rf5 is really the only move to try to gain the initiative ... and I need the initiative if I'm going to get out of this!
Lets look at the possible replies for black:
Qg6, Qh6, Qe3+ & Rxd1 look like the only reasonable tries.
28...Rxd1 29.Rxg5 is exactly what I want & the queen & rook, combined with the f6 pawn, should mate black without too much hassle.
28...Qe3+ looks to be fine for me after 29.Qxe3 Nxe3 30.Rh5+ Kg8 31.Rxd2 Nf1+ 32.Kxg4 Nxd2 33.fxg7 as 33...Kxg7 allows a perpetual with Rg5+ & Rh5+ ... and if the rook moves (say Rd8) then I have Rh8+ skewering the rook & I'm in a favourable rook v knight ending.
This leaves the other two queen moves as the only tries for black ... and they're still rather tricky!
28...Qh6 29.fxg7+ looks like the best try, although Qxg4 might also be worth looking at. 29...Qxg7 looks forced.
If 29...Kxg7 then 30.Qxg4+ Kh8 (or Kh7) 31.Rh5 looks to be winning, or at least drawing. if 30...Qg6 then 31.Rg5 Nxe5 32.Rxg6+ fxg6 and I have the choice between a pretty dead rook ending after 33.Rxd2 Nxg4 hxg4, or a slightly trickier queen v rooks ending after 33.Qe4 Rf3+ 34.Kh4 Rxd1 35.Qxe5+ when I'm pretty sure there's at least a perpetual check there with the queen, if not some method of winning one of the rooks.
So 29...Qxg7 looks like the best try in this line for black. Then 30.Rh5+ Kg8 31.Rxd2 Nxd2 32.Qf4 looks very nasty, with Rg5 & Qxd2 both threatened.
This leaves 28...Qg6 as the only other try for black.
29.fxg7+ again looks like my best option.
If 29...Qxg7 I think the position transposes to the line above after 30.Rh5+ Kg8 31.Rxd2 Nxd2 32.Qf4, which is fine for me.
This leaves 29...Kxg7 as the only other try, and this is the line I'm not entirely convinced about ... the main difference being that the black queen defends the g4 pawn, so I don't have the Qxg4+ I had in the Qh6 lines. The fact that my king is still on the g-file also allows some sneaky gxh3+ lines where it is very easy for me to get into trouble if I'm not careful.
30.Rxd2 looks best, when there are still a few tricky lines ahead.
30...gxh3+ 31.Qg4 Qxg4 32.Kxg4 Ne3+ 33.Kf4 Nxf5 34.Kxf5 leaves me a pawn down in a rook ending, with the pawn on h3 being problematic (if I go after it, I will probably have to lose my e-pawn) as I need to keep an eye on it with either my king or rook, when the passive nature of my pieces may make defending difficult.
30...Nxd2 31.Qxg4 Qxg4 Kxg4 sets up the same Rg5, Rh5 perpetual as in a line above, however its black to move, so it can be avoided, by f6 or moving the rook (to d8, c8, etc). I think this position is lost for me, however the h-pawn provides possibilities for me in the ending, so perhaps all is not completely lost just yet ...

Looks like there's a line I've overlooked ... and I don't like it for white!
Bring on the comments ....

Rg2+ IMO.

Totally overlooked this move. Looks pretty crushing.

I actually did consider this move, unlike so many others he has surprised me with, but I thought I could deal with it in a couple of ways. Now it's looking way more complicated than I thought. And seeing so many posts about it makes me think the game might be back in the balance (or maybe it always was?)

First, I need to look at two forcing tactical lines: Qe3+ and Rg2+, which might lead to straightforward ways to escape with a big advantage. If those are unpromising or unclear, I will move on to Qg6/Qh6.

A. 28...Qe3+ 29. Qxe3 Nxe3 (29...Rg2+ 30. Kf4! Nxe3 31. fxg7+ Kxg7 32. hxg4! and I think Black has to accept the perpetual check on g5 and h5) 30. Rh5+ (I think fxg7 also works, idea is Rg5+ then Kh4) 30. Rh5+ Kg8 31. Rxd2 and now:
A1. 31...Nf1+ was my original plan here 32. Kh4! g6 (32...Nxd2 fxg7=, this is why the K has to be on h4 to avoid f5+ and also gxh5+) 33. Rf2 gxh5 34. Rxf1 and White is maybe even winning
A2. 31...g6 Re2 and again White has done enough to get an endgame that is at least equal

B. 28...Rg2+ 29. Kxg2 (29. Qxg2 Qxf5) Qxf5 30. Qxf5 (forced I'm sure) Ne3+ 31. Kf2 Nxf5 32. hxg4



This is the kind of material-up endgame I was worried about. Sample line: 32...Nh6 (Nh4 is better I think, but still maybe hairy) 33. Kf3 Rc8 34. Rd7 Rxc3 35. g5 Nf5 36. Rxf7 and I don't know who is better here. So I'll come back to this, probably to the Nh4 variation, if Qh6 or Qg6 really aren't good.

C. 28...Qh6 29. Rh1 (29. Qxg4 Rxd1) looks scary.

D. 28...Qg6 and both Rxd1 and gxh3 are major threats. He has a lot of possibilities:
D1. 29. Rh1 gxh3+ 30. Kh4 (Kf4 Rf2+ or Kf3 Qg2+) and now 30...Rfd8 or 30...Rg2 looks crushing
D2. 29. Rxd2 Nxd2 and now:
D2a. 30. fxg7+ Kxg7 31. Qf4 gxh3+ is a nice little trick: Rg5 is met by Ne4+. And if 31. Qxg4 Qxg4+ 32. Kxg4 Rc8 (or anywhere) should be easy
D2b. 30. Qxg4 Qxg4+ 31. Kxg4 (or hx) g6
D2c. 30. Qf4 gxh3+ 31. Kh4 Kg8! intending Qh6+. e.g. 32. fxg7 Rc8, or 32. Rg5 Qh6+ 33. Kg4 g6 34. Qxd2 h2 -+
D3. 29. fxg7+ Kxg7 and he doesn't seem to have gained any possibilities that don't transpose to D1 or D2. e.g. 30. Rdf1 gxh3+, or 30. Qf4 gxh3+ 31. Rg5 Rg2+
D4. 29. Qf4 for completeness (though he'll probably find a 5th move as usual, perhaps he will ignore all my threats and play something like e6 when Rxd1 or gxh3 is surely totally winning) gxh3+ just like D3

In summary, Qg6 looks good and probably simplest

OK, so no Rg2+, which kind of killed me (Kxg2 Ne3+ followed by Nxf5 (or Qxf5), so I'm still alive (somewhat at least) ... although RT did play the best of the moves that I looked at ...
Looks like the plan with 29.fxg7+ is still the best.
Of course it also limits the responses for black (those damn forcing checks!).
Pretty sure I can dismiss Kg8 (gxf8Q+) & Kh7 (gxf8N+), so its only Kxg7 & Qxg7 to consider.
29...Qxg7 is the better line for me (as above) after Rh5+
29...Kxg7 is the trickier line, but the plan is to follow up with 30.Rxd2 & hope to head for the drawish rook ending, or the Rg5-h5 perpetual check ...

Kxg7 is the plan. The king is probably better placed there and the queen covers f5, g5, h5 and e4. Plus Rf8-h8 might be useful, especially if it's checkmate. The only small thing to check is that there isn't a skewer on the g-file: 30. Qf4 gxh3+ Rg5 Rg2+ or 30. Rxd2 Nxd2 (maybe gxh3+ is good) Qf4 gxh3+ Rg5 Ne4+ seems to keep everything in order. Apart from that, I don't see any possible tricks, I should have too many threats.

I have to keep going with the plan ... and hope I can get to an ending I can hold onto ... the analysis is in the posts above, but 30.Rxd2 is pretty much my only option here.
30.h4 was an idea I briefly considered, but that allows 30...Rg2+, which still kills me, so that idea is out the window (at least while the rook is still on d2).
30.Qf4 loses to 30...gxh3+ when 31.Rg5 Rg2+ ends things.
30.Rdf1 is the only other real consideration, but that also leaves me dead after 30...gxh3+.
Of course these lines would suggest that the move toi worry about is 30...gxh3+, and it is the move I'm expecting.
Having said that, the immediate 30...Nxd2 is also fairly strong for black, although at least that lets me get into an ending where I have vague drawing chances.

White's earlier analysis of this was "30...gxh3+ 31.Qg4 Qxg4 32.Kxg4 Ne3+ 33.Kf4 Nxf5 34.Kxf5" but he's just a piece down after 32.-Nxd2, uh oh

A. 30...gxh3+ 31. Kf4 Nxd2 32. Qd4 gives him some chance of tricks.

B. 30...Nxd2 now:
B1. 31. Qd4 Qxf5
B2. 31. Qxg4 Qxg4 32. Kxg4 Re8
B3. 31. Qd3 gxh3+ 32. Kf4 Rh8
B4. 31. Qf4 gxh3+ 32. Kf2 (32. Rg5 Ne4+) Qg2+ 33. Ke1 (33. Ke3 Nc4+ and Rd8+) Nf3+ 34. Qxf3 Qxf3 35. Rxf3 Rh8 36. Rf1 h2 37. Rh1 Kg6

and in all cases White can resign imo

Now I think I have to go into the horrible ending with 31.Qxg4.
As much as I would like to play 31.Qf4, it runs into 31...gxh3 & if 32.Rg5 Ne4+ finishes things. If 32.Kf2 then Qg2+ is winning for black as he either trades pieces off, or has a mating attack.
After 31.Qxg4 Qxg4 32.Kxg4 I have some small swindling chances, based on either the h-pawn causing problems, or tricks involving perpetual check with the rook.
Either way, the thing I need to do is make sure I keep my king & rook active, as this will give me my best chance to salvage something from the position.

I guess he has one more trick: 31...Qxg4+ 32. Kxg4 Nc4?? 33. Rg5+ =. But instead I'll have 32...Rd8, Rc8 or Re8.

Taking the queens off is a no-brainer, it massively reduces the chance of a swindle and I should win the piece-up endgame 100 times out of 100. I could interpose Ne4+ but I think the N doesn't belong there, it will come back to c4.

Not much choice, but Kxg4 has some sort of a threat and rook pawns are tougher for knights to deal with, if it gets that far (though I suspect it won't).
What I need to do ASAP is start attacking the b7 pawn with my rook, to either slow down black's play, or create counter-threats of my own. I also want to make sure my rook & king are actively attacking, rather than passively defending.
I suspect it may be over soon, but no harm in playing on for a few more moves.

Am I the only one thinking it would be nice to resign at this point? Down a piece for a pawn, no counterplay at all.

hey he IS threatening a perpetual

No, he thinks about:

his threat is Rg5+ drawing. I don't think it matters too much how I meet this: Rc8, Rd8, Re8 or even Rh8. f6 is also possible but I'd rather hang onto this pawn for a little while/not allow e6.

Rc8 seems the most logical (originally I thought Re8, but I can't actually win that pawn). I can come to c4, c3 or c2. The only drawback is I can't come to c5. In fact Rc4+ is probably a threat, so he should play

32...Rc8 33. Rg5+ Kf8 34. Kf5 Ke7 and now:

A. 35. h4 Nf3 36. Rg4 Rxc2 with fairly big plans of knocking off the h-pawn.
B. 35. Rg7 Nf3 36. Ke4 Rc3 should hold back any ideas he has of e6.

h4-h5-h6-h7-h8 is his only real threat and it takes a long time and I should be able to cover it easily with my pieces. If absolutely necessary, I can take a queenside pawn or two and give up my knight for the h-pawn at some appropriate moment when I have a clearly winning rook ending. But basically I'm a piece up in the endgame, under no real pressure, and expect to win comfortably.

White resigns here, imo