I think Black is going down the wrong path here. The position after 23.Qd2 Ne3 24.Re1 Nxc4 25.bxc4 looks strategically hopeless for Black. I don't see why Black suddenly decided to reject his original plan of Kc7.

I completely agree. Black is only wasting tempi by playing N -> e3 -> c4 whilst white develops his pieces. After the exchange either white's N is coming to e4, or black has to play f5 creating an outpost on e5. All the while the B on a7 and R on a8 look useless.

Ah, right, my bishop was also guarding e3. It was actually fairly well placed on c1. Anyway, Black now threatens ...Ne3, forking my queen and rook as well as sitting uncomfortably deep into my position and close to my king. Maybe it's time to re-claim the e-file:
23. Re1 Ne3 24. Qd2 (maybe Qh5?) Nxc4 25. bxc4 b5 26. axb5 axb5 27. Nxb5 Bxb5 28. cxb5 is fine as it wins a pawn, so the plan to play ...b5 doesn't yet work, at least. Black may try 24...Qe7 ah! but then 25. d6 wins.

The knight is also aimed at h2 currently. I don't think an immediate knight-sack works: 23. Re1 Nxh2 24. Kxh2 and I just don't see how this works, though it may be slightly uncomfortable. Oh, I'm 1 step ahead of myself: 23. Re1 Qh6!. Well, then 24. Qd2 fixes that problem. Maybe Black would prefer 23. Re1 Rxe1+ 24. Qxe1 Qh6 but then 25. Qd2 still solves my problems (or maybe 25. Qe2, planning Re1 and Qe7+ if that helps ever).

I also need to check if Black tries the moves I looked at last move as now he has a knight and bishop aimed at f2: 23. Re1 b5 24. axb5 axb5 25. Nxb5 Bxb5 26. Bxb5 c4+ 27. Rxa7 Rxe1+ 28. Qxe1 Rxa7 29. Qe8+ Kc7 30. Qxf7+ and I think I'm winning more pawns despite being down the exchange (with a threat of h3 and Be5 looming). Assuming I didn't miss something in this long line.

Is there better than 23. Re1? Maybe playing 23. Qd2 first, but I'm not sure what that gains except avoiding 23...Rxe1. To be honest, I think I'd be happy with the rook trade as it gives me the e-file. I could try 23. Qf3 Ne3 24. Rfe1 Bg4 25. Qf2, but I don't want my queen skewered to my king, so no.

If 23...Rxe1+ then 24. Qxe1

amazing

You might be joking but that is the game's best example of how to use conditional moves

It is. I was amused by the contrast between ****'s and ganstaman's conditional move philosophies -- the simplicity of ganstaman's spoiler in contrast to ****'s earlier maximalism.

24. Qh5 is gonna spoil my k-side pawn structure, but in absence of the white LSB, the f6-g6-g7 pawn fist is gonna be invincible, at least at first.

If he exchanges rooks on e8, I'm gonna recapture with the king, then move it to out to f8, except for maybe the 25. Qh5 case because 25. Qh5 Nxc4 26. Rxe8+ Kxe8 runs into complications:

27. Qxh7 Nxb2 28. Re1+ Be6 (Kd8 29. Qh8+ Kc7 30. Qxa8) 29. dxe6 c4+ 30. Kg2 (30. Kf1 Qd3+ 31. Qxd3 Nxd3, 30. Kh1 Qc6+ 31. Re4 {Qe4 Qxe4+, Ne4 Ke7} f5 32. Qxf5 {Qg8+ Ke7 33. Qxa8 Bd4} fxe6) Bc5 31. e7 (31. Qg8+ Qf8) Qc6+ 32. Re4 (Kh3 Qh6+, Ne4 Kxe7) Bxe7 33. Qg8+ Kd7 34. Qxa8 f5.

It looks like Black is winning in the end, but these lines have to be examined more thoroughly before committing to 26... Kxe8, I'm sorry if I'm written nonsense somewhere because I've just woken up from a nightmare and am very groggy

If 24. Qh5, then 24... Nxc4 25. bxc4 Qg6 26. Qxg6 hxg6 27. Ne4 f6.
If 24. Qd2/Qc1, then 24... Nxc4.
If 24. Qe2, then 24... Bg4 25. Qd2/Qf2 Nxc4.
If 24. Qd3, then 24... Bf5 25. Qd2 Nxc4.

He can play 25. Qh5 Nxc4 26. Rxe8+ first, though, and then there will be less fun because, after 26... Kxe8 27. Re1+ Kd8 28. Qxh7 Nxb2 29. Qg8+ Kc7 30. Qxa8 Qb8, the material would be about equal, and I'm not sure if I should recapture with the king at all. Doing it with the bishop looks safe anyway, just a bit passive.

Ah good, more or less what I expected. The plan from before is 24. Qd2 to protect the queen while forcing the knight to leave e3. It is important to note that in the event that Black passes on his next move, after 25. Rxe3 Rxe3 26. Qxe3 b5 27. axb5 axb5 28. Nxb5 (well, probably 28. Bxb5, but to demonstrate my point we'll take with the knight) Bxb5 29. Bxb5 c4 pins my queen to my king, but I can simply take the bishop with 30. Rxa7.

I mentioned last time possibly 24. Qh5, but after 24...Qg6 I'm not sure that I really accomplished anything. I'd like to keep the queens on as I think I can make use of mine and Black is still a bit cramped so I don't want to trade off pieces without good reason.

I can also consider 24. Qf3 as that's not a bad looking place for the queen. If 24...Bg4 25. Qf2 and while I mentioned before that I can be safe on that a7-g1 diagonal sometimes, it just seems riskier than being on d2. Something else that I have to look at though I doubt it really works is 24. Qf3 Bg4 25. Qxe3 Rxe3 26. Rxe3, trading a queen for R+N. If Black responds by trying to pin my rook to my king: 26...b5 27. axb5 axb5 28. Rxa7 Rxa7 29. Nxb5 Qb6 30. Nxa7 Qxa7 31. Bxg7 planning Bf6+ seems to have potential, especially as I've won 2 pawns in this. Though 31...Qb6 might end those plans. Also, 29...Qg6 30. Nxa7 Qb1+ 31. Kg2 Qxb2+ 32. Kg1 Qa1+ and Qxa7 is bad for me. I'd be interested to know if I missed some tactic in this line.

Something that just popped into my mind is 24. Qd2 Nf5, planning ...Nd4. Then 25. Ne4 Qg6 with plans to play ...Ng4 or ...Nd4, opening up a second piece on my once defended knight and threatening ...Nf3+ with a family fork. If I block both of these threats with 26. Qg2 then 26...b5 is actually rather annoying. Maybe I shouldn't move my knight, then? I considered 24. Qd2 Nf5 25. a5 to put an end to the ...b5 threats, but then 25...Nd4 again threatens ...Nf3+. So if 26. Qf2 Nxb3 27. Bxb3 c4 wins my queen. 26. Qg2 Qh6 threatens ...Bh3.

Perhaps what's needed is 24. Qd2 Nf5 25. Rxe8+. If 25...Bxe8, then the bishop is a tempo off from the above lines. It also allows me onto the e-file. But I'm still not sure if it concretely helps me. I've been staring at this position for too long, so let's try one more thing: 24. Qd3. If 24...Bf5 25. Qd2 and I'm good as the f5 square is blocked from the knight. If 24...Nxc4 25. bxc5 b5 26. axb5 axb5 and maybe 27. Kh1 or 27. Ne4 (not 27. Nxb5 Bxb5 28. cxb5 c4+ winning my queen). Oh, but how does this help if 24...Nf5? Ah, 24. Qd3 Nf5 25. Rxe8+ Kxe8 26. Re1+ blah blah blah, if ...Nd4, my queen on d3 has f3 covered. I just have to move my knight and my queen also has b3 covered. Also, perhpas I could play 24. Qd3 Nxc4 25. Qxc4 b5 26. axb5 axb5 27. Nxb5 Bxb5 28. Qxb5 Rxe1+ 29. Rxe1 and my pressure on e8 looks nice.

This better not be a case of "when you analyze a bunch of moves and reject them, analyze a blunder just a little and play it as you didn't look deeply enough at it."

Maybe I've missed smth stupid, but I can't take the conditional move back.

Looks pretty good for Black.

25. Qd2 Nc2 (headed to d4), not 25.-Nxc4.

I suspect he's thinking about 25. Ne4, with idea of 25... Rxe4 26. Rxe3, retaining the material balance and possibly getting more active pieces, which doesn't look disastrous for me quite yet anyway, at first sight. But hang on a sec, if I play 25... Nxc4 26. Nxd6 Rxe1+ 27. Rxe1 Bxd3 28. Re8+ (if 28. Nxc4 g6, I've just got a bishop pair vs an IQP; 28. Nxf7+ Kd7 29. bxc4 Bb8 [preventing Ne5+] 30. Bxg7 Bxc4 31. Rc1 b5) Kd7 29. Rxa8 Nxb2 30. Rxa7 Kxd6 31. Rxb7 Bg6 32. Rb6+ Kxd5 33. Rxa6 Bc2, isn't that decent for me? (Again, I'm calculating blindfolded, so excuse me if I've made some mistake.) Hmm, there are some deep lines here, they need more though obv.

Edit: 25... Qg6 26. Rxe3 b5 27. axb5 axb5 looks even more promising, it looks as though White has to lose the exchange for a pawn due to my a7-h2 diagonal control: 28. Bxb5 c4 29. Qd2 Bxe3+ 30. Qxe3 Rxa1+ 31. Bxa1 Rxe4 or 28. Rxa7 Rxa7 29. Bxb5 Rxe4.

30. d6!! and the dual threats of Ne5+ and Re7+(/d7+) can't be met. The point is 30.-Bxd6 31. Nxd6 Kxd6 32. Rd1, and 30.-Kc8 31. Re8+ Kd7 32. Re7+, which picks up material.

Concrete chess is the best. Great line, and props for noticing 25. Ne4 -- it's a very counter-intuitive move.

Note that, in the 25. Qd2 line, as it would be in the 24. Qd3 b5 line I've ditched so lightly, the b5 break doesn't work because White doesn't have to move the LSB out in this case - he can just give it up for the e3 knight, remaining with an extra (protected passed) pawn.

In the 25. Ne4 Qg6 26. Qxe3 line, I think I have 26... Rxe4 and the same idea with the activation of the a7 bishop as in the above post.

25. Ne4 Rxe4 26. Rxe3 b5 27. axb5 axb5 28. Rxa7 Rxa7 29. Rxe4 Bxe4 30. Qxe4 bxc4 31. Qxh7 is not so good for Black.

25. Qe2 pins the e3 knight too, but I can remove the pin by playing 25... Bg4, and if 26. Qd3 Nxc4 27. Rxe8+ Kxe8 28. Re1+/Qxh7, the positive difference for me is that I now have the d7 square available for the king.

25. Ne4 Bxe4 might be more better than Qg6, though, due to the same b5 break, but I won't spend any more mental energy until Ne4 is actually played

yeah Ne4 is a pretty sweet move, if it's actually any good it should go in a puzzle

He's committed to playing Nxc4 from his conditional move though, right? (if I'm understanding the rules of this correctly)

Not if he updates it before Qd2 is played. He probably won't, but whatever.

Ok, so I'm moving my queen. I have 3 moves that need to be investigated -- 25. Qxe3, 25. Qe2, and 25. Qd2. All others lose rather quickly, I believe.

25. Qxe3 is similar to what I analyzed last time, but with Black's bishop on g4 instead of f5. I don't think this makes a difference. I still don't like this.

25. Qe2 pins the knight, but doesn't actually threaten it. If Black responds with 25...Kd7, the pin is broken and my queen becomes a target that must now move again. Maybe 26. Qh5 but 26...Bg6 and it's no fun for me.

So the winner by default is 25. Qd2. I expect 25...Nxc4 26. bxc4 and then who has a clue?

Btw, for a moment I looked at 26. Rxe8+, intending 26...Kxe8 27. Qe2+ Kf8 28. Qxc4. But I don't know that I really prefer my queen on c4 vs my pawn, and 26...Kd7 27. Qe2 Rxe8 28. Qxc4 gives Black the e-file for nothing. Maybe there's better in this line, but it didn't seem likely enough to investigate further.

In general, I need to connect the rooks to avoid giving the e-file up (i.e. to disallow Rxe8+ Kxe8 Re1+ and Qe2/e3).

I don't think I'll need the bishop on d7 in the near future; it's standing nicely on f5, guarding the e4 square. I might need the c7 square, though, or to install the bishop on d6 to block the pawn, so I think the d7 square is more preferable to c7 for the king.

Sorry for not thinking in concrete lines, I yet have to internalise the 'show, don't tell' guideline given by Rei.

If 27. Rxe8, then 27... Rxe8.
If 27. Ne2/Na2, then 27... f6.
If 27. Nd1/b1, then 27... Rxe1+ 28. Qxe1 Re8.

That one is fine imo, since it is a simple binary decision. Sometimes it's not practical or necessary to calculate a bunch of concrete lines, but if you have the time, I don't think it can hurt.

One move that you should look at and rule out, in addition to the bishop-knight discoveries on g7, is the newly created "threat" 27. Re5 -- it attacks a hanging piece (and offers a pawn sacrifice ), it would facilitate an e-file doubling if just left there, plus there's some tactical geometry along the big diagonal. 27.-Rxe5 28. fxe5 Qxe5 29. Nb5 Qe7 30. Re1 Qd8 31. Qf4 is bad for Black, but alas, 29.-Qe4 seems to hold things together.