White develops his other bishop.
5. ... d6
Black also frees his bishop.
Let's take a look at white's strategy now by examining the three sections of the board.
Black has a pawn clamping down (c5) and a powerful bishop (Bg7 covers diagonal all the way to a1). White really can not make any successful pawn breaks or create play on the queenside.
The d4 break is prevented by black. White can not open the center or create play there either.
White's play MUST proceed on the kingside. White will wait for black to castle and build up an attack.
Let's proceed a little ahead and then take a look at black's strategy.
Since we have deducted that white's play is on the kingside, white grabs a little more space on that sector.
A later pawn push to f5 may also be in the cards.
6. ... e6
6. ... Nf6 is also very logical. Spassky's win over Geller took this move off the map, but Kasparov's use of it later revived it.
By playing 6. ... e6, black intends Nge7.
On e7, the king's knight is less of a target for white's intended attack/pawn avalanche (f4,h3,g4,g5,etc).
White won't be able to gain time kicking the knight around, like he would were it on f6.
White simply develops his last piece and prepares to castle.
7. ... Nge7
Black does likewise.
White gets the king out of the center and waits to see what black does next.
Black also removes his king from the center.
Now, lets look at black's strategy.
Black will try to keep white's kingside attack at bay. One advantage of Nge7 over Nf6 is that g4 (eventually), with the intention of f5 by white, can be met by f5 from black. This kills white's chance of playing f5 himself and clamping down on the kingside.
Black can also play Nd4 and recirculate the e7 knight to c6 for more central control.
Just be sure to leave the d4 knight a way out if he can be attacked.
Black's main strategy, however, is a queenside counterattack.
Black's logical strategy will be Rb8, b5, b4, a5, a4, a3 (not necessarily in that order).
This attacks the queenside, attempts to make white create holes, and tries to open the strong bishop on g7's diagonal even further.
All of the play commences on the dark sqaures, hence the dark square strategy.
To counter this, white needs to get at the kingside without making too many concessions on the queenside.
White is also always on the lookout for a chance to get in the d4 push, blasting open the center.
An open center would make black's slow queenside ambitions bear less fruit.
These are the basic aims of each side in this position.
White develops a piece and prepares the possibility of slipping in d4.
After d4 and a c pawn trade on d4, black would have a backward d6 pawn on an open file!
This would be a serious weakness and tie black down considerably.
9. ... Nd4
! This prevents d4. Black gets a little space in the process.
Black's plan is still Rb8, b5, and b4 with a pawn assault on the queenside.
I hate to leave it off here, but this is just a general discussion of the opening.
From this position, white has tried many moves.
Most can be met with black's queenside pawn attack idea.
White's only real try to complicate or trip black up is 10. e5 !? .
Slower moves don't give white much at all.
I will just give one line to show how the came can proceed after 10.e5, so as to not leave the readers in the dark.
10.e5 Nef5 11.Bf2 Nxf3+ 12.Qxf3 Nd4 13.Qd1 dxe5 14.fxe5 Bxe5 15.Ne4
Here are all 15 moves in pgn.
For more analysis or alternatives, consult a book on the Closed Sicilian.
I hope everyone enjoys this commentary, and I hope it helps players to learn something about overall game strategy.
I picked this variation because the play is very thematic.
I will post the tactics section in a few days.