Move 30
 

Well, I assume they must have worked out a pretty win after 30...Rxb7.

A quick look has turned up this quite funny perpetual check 30...Rxb7 31.Ra8+ Kg7 32.Qg3+ Kf6 33.Rf8+ Qxf8 34.Qg6+ Ke5 35.Qe6+ Kf4 36.Qe4+ Kg5 37.Qg4+ Kf6 38.Qg6+ (round and round). But they have no doubt got a win instead of this.

Whatever, I think we are forced to play 30...Rxb7 anyway because they are threatening the devastating Ra8 after which neither ...Qf8 (they play Qh3+) nor ...Qc1+ (they play Qf1) will save us. 30...Kg7 doesn't help us because of 31.Bc8 followed by 32.Ra8.

So unless you two spot anything for us which I've missed, I would suggest we play 30...Rxb7 and allow them to demonstrate the win they've worked out.

EDIT: Now I do spot something else for us: 30...Qf4 lets us threaten mate in two and so prevents them playing Ra8. I guess we need to find out what they have worked out if we play 30...Rxb7.

[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]

1. d4 Nf6 2. c4 c5 3. d5 b5 4. cxb5 a6 5. b6 Qxb6 6. Nc3 g6 7. Nf3 Bg7 8. e4 O-O
9. Be2 d6 10. O-O Nbd7 11. Nd2 a5 12. a4 Ba6 13. Nb5 Rfb8 14. Nc4 Qd8 15. Qc2
Ne8 16. Bd2 Bxb5 17. axb5 Nc7 18. Bxa5 Qc8 19. b6 Nb5 20. Bg4 Nd4 21. Qd3 f5 22.
exf5 Ne5 23. Nxe5 Bxe5 24. Bc3 Rxa1 25. Rxa1 gxf5 26. Bxd4 Bxd4 27. Bxf5 Qf8 28.
Bxh7+ Kh8 29. Bf5 Qh6 30. b7 Qf4 (30... Rxb7 31. Ra8+ Kg7 32. Qc2 (32. Qg3+ Kf6
(32... Kf7 33. Be6+ Kf6 34. Qf3+ Kg7 35. Rg8+ Kh7 36. Qf5+) 33. Rf8+ Qxf8 34.
Qg6+ Ke5 35. Qe6+ Kf4 36. g3+ Kg5 37. Qg6#)) (30... Qf6 31. Qh3+ Kg8 32. Qh7+
Kf8 33. Ra8) (30... Qf8 31. Qh3+ Kg7 32. Qh7+ Kf6 33. Qg6+ Ke5 34. Re1+ Kxd5 35.
Qe6+ Kc6 36. Qc8+ Qxc8 37. bxc8=Q+ Rxc8 38. Bxc8) 31. Qc2 Rxb7 (31... Kg7 32.
Ra8 Rxb7 33. Be6 Qh6 34. Rg8+ Kf6 35. Qf5#) 32. Ra8+ Kg7 33. Be6 Qf6 34. Rg8+
Kh6 35. Qd2+ Kh7 36. Qd3+ Kh6 37. Qh3+ *

Could you identify what you consider the main line following 30...Rxb7 in all that, WMH?

I get 30...Rxb7 31.Ra8+ Kg7 32.Qc2 and then...?

EDIT: Now I see you've put it in a subvariation: 30...Rxb7 31.Ra8+ Kg7 32.Qg3+ Kf6 33.Rf8+ Qxf8 34.Qg6+ Ke5 35.Qe6+ Kf4 36.g3+ and mate next.
Okay, that's clear. Do you think we should play that, or play 30...Qf4, or 30...Qf6, or resign?

That was a quick analysis I haven't gone into any depth on the other moves yet.

I'd say Rxb7 is forced, so by yours and my strategy of preserving
excess thought, let them make their next crusher move.

[QUOTE=davar55;412779]I'd say Rxb7 is forced, so by yours and my strategy of preserving
excess thought, let them make their next crusher move.[/QUOTE]
I think you may well be right in that their threats of Ra8 and Bc8 seem to be crushing, and so even though WMH has demonstrated a forced mate for them following 30...Rxb7 it may be the right thing to do.

However, perhaps 30...Qf4 is worth a try instead. The point of this is that they cannot reply 31.Ra8?? Qxf2+ 32.Kh1 Qg1 mate.

30... Qf4 31. Qc2 Rxb7 32. Ra8+ Kg7 33. Be6 Kh6 34. b3 (34. Rg8 Qf6 35. Qd2+ Kh5 draws)

[QUOTE=WMHalsdorf;412852]30... Qf4 31. Qc2 Rxb7 32. Ra8+ Kg7 33. Be6 Kh6 34. b3 (34. Rg8 Qf6 35. Qd2+ Kh5 draws)[/QUOTE]
Yep, we're still alive here.

It seems to me that we must play 30...Qf4 because it's the only move where their win is not absolutely clear. But what do you both think now?

[QUOTE=Brian-E;412877]Yep, we're still alive here.

It seems to me that we must play 30...Qf4 because it's the only move where their win is not absolutely clear. But what do you both think now?[/QUOTE]

It probably offers the best chance for a draw.

Okay then.

davar55, would you be okay with 30...Qf4 ?

What if 30. .. Qf4 31. Qa6 Qxf2+ 32. Kh1 .. Qxb2 33. Qa7 .. (aiming at QxRb8 or b8(Q)) ?

Oops our Q might grab their Bf5 in the middle of that.

If you run out of time though, I'm ok with Qf4.