Its difficult to imagine how the Black K has arrived here so early.

1. One way is to support the e5 N with d4. The Black K is then left with only one move, kf5. Qg4, a serious threat then looms. But Black has h5 counter.

2. The other way is to play Qg4 at once and pull the Black K further up into a precariously lonesome zone.

It looks very vague today but I'll try and go some of the way;

9. Qg4+ Kxe5 10. d4+ Ke5 (Kxe4 leads to mate on the move 11. Qxf4#) 12. Bxf4+ Ke4 13. Qf3+ Kf5▢ 14. Bxc7+ and the Black Q is bagged.

<13.Qf3+ Kf5 14.Bxc7+ Kg6 15.Bxd8 Bxd8>

But it is not the first time for Korchnoi.
See here, exactly 50 years after the game above.
Kasparov vs Korchnoi, 2001

It's the game against Kasparov, at the "Korchnoi's birthday" in 2001.

After 21. Rf3+ any players would have resigned, do you think that Kasparov can miss a mating, do you believe he can fail to calculate 7 moves?

But Korchnoi took the Knight, and went on with his poor chased King for several moves, resigning just one move before mating (26.g3+).

In the sort of position dear to the heart of every Traxler player, Black's king is his most active piece, so White invites it in for a tainted meal that it's apparently too famished to refuse:

9. ♕g4†, ♔xe5 ▢;
10. d4†, and Black has two options for his next course:

(1) 10. ...♔xe4?;
11. ♕xf4# or

(2) 10. ...♔xd4;
11. c3†, and now Black has four choices:

(2.1) 11. ...♔d3?;
12. ♕e2#

(2.2) 11. ...♔c4?;
12. ♕e2#

(2.3) 11. ...♔xe4?;
12. ♕xf4†, ♔d3 ▢;
13. ♕d4†, ♔c2 ▢;
14. ♕d1#

(2.4) 11. ...♔e5. Now White is at a crossroads: He can regain material equality and retain some attacking chances against Black's exposed king:

(2.4.1) 12. ♗xf4†, ♔xe4 ▢;
13. ♕f3†, ♔f5 ▢;
14. ♗xc7†, ♔g6;
15. ♗xd8, ♖xd8 . Or he can play more speculatively for a continuing assault on the black monarch:

(2.4.2) 12. ♕xf4†, ♔e6 ▢;
13. o-o. Here Black must be careful:

(2.4.2.1) 13. ...dxe4?;
14. ♕f7†, ♔d7;
15. ♖d1†, ♔c6;
16. ♕c4†, ♗c5†;
17. ♗e3! and the game might finish
17. ...♘a6;
18. b4, b6;
19. ♕xe4†, ♔b5;
20. a4#

(2.4.2.2) 13. ...♖f8?;
14. ♕g4†, ♔e5 ▢;
15. ♗f4† and one of

(2.4.2.2.1) 15. ...♖xf4;
16. ♕xf4†, ♔e6 ▢;
17. ♕f5# or

(2.4.2.2.2) 15. ...♔xe4;
16. ♖ae1†, ♔d3;
17. ♕e2#.

However, Black seems able to wreck the entire plan with

(2.4.2.3) 13. ...♔d7! .

9.Qg4+ Kxe5 10.d4+ Kxd4 11.c3+ Ke5 12.Bxf4+ Kxe4 13.Qh5 leads to forced mate:

13...g5 14.0-0-0 Kf5 15.Rde1 Kf6 16.Bxg5+ Kg7 17.Bh6+ Kg8 18.Rhf1 Be6 19.Rxe6 Bg5+ 20.Kb1 Bf4 21.Re8+ Qxe8 22.Qxe8#

13...Bg5 14.0-0 Re8 <14...Kd3 15.Qe2+ Kxe2 16.Rad1 Bxf4 17.Rfe1#> 15.Rae1+ Kd3 16.Qd1+ Kc4 17.Qa4+ Kc5 18.b4+ Kc4 19.b5+ Kc5 20.Qd4+ Kxb5 21.Rb1+ Kc6 22.Qa4+ Kc5 23.Qb5#.

9.Qg4+ Kxe5 (forced)
10.d4+

a)10..Kxe4
11.Qxf4#

b)10..Kxd4
11.c3+
Four possible moves now for King:

9.Qg4+ Kxe5 (forced)
10.d4+ Kxd4
11.c3+
b.iv)11..Ke5
12.Bxf4+ Kxe4
13.Bg3+>?
13...Bxg4 and white loses.

<Once> upon a time there were two bulls who lived in a farmer's field. One bull was old and wise, the other was young and eager. You can imagine that Bull #1 was on his last legs and that Bull #2 was his padawan apprentice, if you are into that sort of thing.

One day, the farmer opened the gate to the field to allow the bulls into the field with the laydee cowz. All at <once> the young bull starts running for the gate, anxious to ... ahem ... get with the laydeez.

The old bull snorts in derision: "Why the rush, my young apprentice?"

"But, but, my leathery master! The gate is open. The way is clear. If we are quick we might attend to half the herd."

The old bull chews the cud contentedly. "Yes, but if we walk we might have the energy to service all of them."

And so it is with king hunts. The temptation is to rush, to sacrifice more and more of our pieces and our energy. But we need to conserve just enough to finish the job off. Chasing our quarry all round the field is all very well, but we need to be able to ... ahem ... carry out the mating attack when we've cornered them.

This is the key position after 13. Kf5:

click for larger view

White has a decision to make. Does he carry on chasing with an aggressive castling move (on either side) or another check? Or does he bail out into a material plus with Bxc7+/Bxd8?

It would be dreadfully shameful to win the chase but not to have the energy to finish the job off. White has invested two minor pieces in this attack. He does not want to see the black king run to safety on g8.

White decides (rightly) to grab the black queen and only the to continue the chase. So we get 14. Bxc7+ Kg6 15. Bxd8

click for larger view

You might be tempted to stop there, but this is a surprisingly interesting position. White has sacrificed three minor pieces to win the black queen. In theory, this is material parity. All black needs to do is to hide his king somewhere and a tense middlegame/ endgame will start.

And if that happens, we might have the funny sight of a young bull having expended all his energy getting to the herd that he has no va-va-voom left to ... earn his living.

What should black play next? Funnily enough, our first instincts may well be wrong. 15...Rxd8 seems to be the natural move. It develops a piece, gives the illusion of Rd6-f6 and suggests that black may yet "castle by hand".

But Fritzie is adamant that 15...Bxd8 is the better move. The problem with 15...Rxd8 is that the rook on d8 is a new target for white. In some lines, this rook can be won with the tactic Qg3+/ Qc7. For example, after 15...Rxd8 16. 0-0 black would love to play 16...Bf6 dreaming of Kf7-Kg8. But white can cross this with 17. Qg3+ Kf7? 18. Qc7+

By contrast, Bxd8 does allow for the Bf6 defence. Black is still going to lose but there is no quick mate in sight.

So to dispel some myths: (1) This king hunt doesn't lead to a forced mate against best play. (2) Winning black's queen does not mean that you've won the game. Three minors can hold a queen back. (3) Korchnoi had a good reason to play on as the outcome was by no means certain. (4) 15...Bxd8 seems better than 15...Rxd8

White has burned his boats and may as well continue the attack: 9.Qg4 Kxe5 10.d4+ Kxd4 11.c3+ Ke5 and this is as far as I can confidently visualise from the puzzle position. Before checking I exceptionally decided to set the puzzle position

click for larger view

up on Crafty End Game Trainer http://www.chessvideos.tv/endgame-t... and by trial and error found 12.Bxd4+ Kxe5 13.Qf3+ Kf5 14.Bxc7+ Kg6 15.Bxd8 Rxd8 and now I would like to castle but the robot doesn't allow this move. So it now is indeed time to check:
===
I have indeed found the game continuation and White continued 0-0. To continue using Crafty EGT, I need to set this position up with the King on f2, White to play and complete castling KR with the move Kg1. Further link: http://www.chessvideos.tv/endgame-t...

The ingenious robot prefers 16...Kh6 to leave

click for larger view

It still makes an appearance from time to time. Take a look at this game for example:

The most forcing is <9.Qg4+ Kxe5 10.d4+!>.

10...Kxe4 11.Qxf4#! This wasn't immediately obvious to me at first.

Black threatens 9... Kxe5 and 9... dxe4.

The first move that comes to mind is 9.Qg4+, forcing the extraction of the king, 9... Kxe5 10.d4+ Kxd4 (10... Kxe4 11.Qxf4#) 11.c3+

A) 11... Kxe4 12.Qxf4+ Kd3 13.Qd4+ Kc2 14.Qd1#.

B) 11... Kd3(c4) 12.Qe2#.