Abdel Irada: ∞
<<•> Strategic tactics? <•>>
I almost feel that I'm missing something, for the winning sequence in this puzzle is forthright, positional and involves no sacrifice. White's initial moves could in fact be considered as much strategic as tactical. Victory is won through sheer irresistible pressure.
The sole pitfall against which White must guard himself is his own impatience.
<<•> 29. Bxe6, fxe6 >
No option is (a) 29. ...Rxe6?? 30. Rd8†, with mate in one.
White has weakened Black's pawn structure and particularly his kingside, seizing access to vital squares. One could not find a better positional choice (and that it contains more than a drop of cyanide is only so much to the better).
<<•> 29. Rd7 ... >
Here is where White can go wrong with 29. Qg6?!, which allows Black to save himself with 29. ...Qa4. (Analyze the results, and see for yourself why treading a straight path sometimes demands that we first examine the full course of the crooked.)
Again, however, White is positionally correct: His rook has seized the seventh rank with pressure against one of those vital squares (and again there is tactical venom in the move, but that still remains in the realm of omen and far-heard prophecy; what will actually befall Black still depends upon his choice, and he has two real ones).
< (1) 29. ...Qxc4 >
No better is (b) 29. ...Qa4 30. Qb7 , when Black has no way to stop 31. Rxg7†, Kh8 32. Rh7†, Kg8 33. Qg8 (or some similar sequence), except by giving up his queen for a rook, which is slower death but death even so.
< 30. Qg6 ... >
Very forthrightly, White threatens a multitude of mates. Still no sacrifice, and none of our accustomed "flash."
< 30. ...Qf4† >
This is desperation, but what choice is there? Black has no means to guard against every threat, save only this one gamble: "Will White, with one slight test to pass, just possibly go awry in the moment of victory? (Such has, after all, happened before.)"
< 31. Rg3 >
We complete a straight path. Now there are three White heavy pieces biting on g7, and Black cannot save himself.
(Crooked option: (c) 31. g3??, Qf2†, and *somebody* is about to get crushed, but unfortunately it isn't our opponent.)
Meanwhile, Black has another defensive idea. so we must also dispose of that.
< (2) 29. ...Kh8 >
Here White can walk a crooked path (as to our "positional" theme) straightly, for (d) 30. Rxg7!, Kxg7 31. Rg3† mates quickly. But is this necessary?
< 30. Qg6, Rg8 >
This of course was the point of Black's king move. Will it be enough?
< 31. Rg3 >
No fireworks. No "tactics" as most puzzles would have them; they are possible but not necessary. Again, I am fallible and may be missing a defense to this series of "quiet" moves, but if so, blind to it I remain.
If the foregoing analysis is correct, the constant White "overattack" would seem to be a chessic version of the pragmatic military doctrine: Attack only with preponderant force. White can, but need not, take chances, and Black will meet his death by pressure rather than by blows.