1. d4 c5 2. d5
A lot of people play it against me as black, and I am also interested in it for both sides.
What are some of the main lines? Also, what are some of the key positions and ideas?
As white I have had a pretty easy time following up with the moves c4 - Nc3 - e4 - f4. Black will usually play e6 and exd5 - respond with cxd5. White ends up with a ton of space in the center. Look up the Taimanov variation in particular.
Basically I got this from MCO15 - the author mentions that many players use a different move order to reach the Benoni just to avoid this setup (they wait for white to play Nf3 blocking the f pawn).
How should I play the Old Benoni Defense as both White and Black?
Let me justify that a little. The Benoni is a very combative opening from both sides of the board. Many lines are extremely sharp, especially in the Old Benoni where White has all kinds of weapons at his disposal, like the ultra-sharp Taimanov (
1.d4 c5 2.d5 Nf6 3.c4 e6 4.Nc3 exd5 5.cxd5 d6 6.e4 g6 7.f4 Bg7 8.Bb5+):
[Opening "Benoni, Taimanov Variation"]
[FEN "rnbqk2r/pp3pbp/3p1np1/1BpP4/4PP2/2N5/PP4PP/R1BQK1NR b KQkq - 2 8"]
In modern lines, Black usually waits a move or two before playing
...c5, to avoid some of the more popular "anti-Benoni" systems. Specifically, Black often wants White to commit a Knight to
f3, so that there's no immediate fear of
f2-f4. However, the Old Benoni is certainly still playable as long as you're ready for a highly tactical struggle.
In the main lines, Black usually plays
...e6 and then exchanges his e-pawn for White's d-pawn. This gives Black a queenside majority and White a central/kingside one. Black will then blockade the advanced d-pawn by playing
...d6, and then usually fianchetto the King Bishop to take advantage of the strong diagonal controlled by his pawns on
d6. Meanwhile, White will use his advantage in space to make threats in the center and on the kingside.
This opening presents a variety of opportunities for tactical combinations. Because the center is semi-closed by the pawns on
d6, it can be difficult to effectively switch pieces from one side of the board to the other, especially for Black, who has less space in which to operate. This tends to result in a game where counterattack is easier and more productive than defense.
White's most important positional advantage in the Benoni is his central pawn majority. In particular, the threat of White's eventual
e4-e5 is often a major point of contention for the early part of the game. White normally will castle kingside and play
Re1 to support this advance, and may also play
f2-f4 as well.
As the game progresses, White may also find a variety of very strong central outposts for his Knights, depending on which pawn advances Black ends up making.
e4 are often good candidates, and sometimes even
White enjoys extra space in the center and on the kingside, so his general plan is usually to pressure the center until he can either break through there, or spill over onto Black's castle. Besides the
e4-e5 pawn push, White may also put pressure on Black's backward pawn on
d6 with moves like
Nb5, and sometimes
Since Black will frequently be trying to make headway on the queenside, White has an interest in preventing him from gaining much space over there. To this end, White often plays
a2-a4 and may try to land a piece on
b6 to prevent Black's
b7-b5. If White can manage to maneuver a Rook to
b6, Black will be very hard-pressed to hold onto his backwards d-pawn. Tactics involving sacrifices on
d6 are also relatively common, where White can make his central pawns into passers by force, and from there drive the game home.
[White "Jonathan Penrose"]
[Black "Mikhail Tal"]
[FEN "1rb1r1k1/2qn1pbp/3p2p1/1pnP4/2p1PP2/2N1B1NP/1PB2QP1/R4RK1 w - - 0 1"]
Black has two key weapons in this opening: his queenside pawn majority and the half-open e-file. Because White's pawn center is fairly advanced, these two factors can combine to allow Black to undermine the White center with well-timed queenside pawn thrusts (
...c5-c4 is often a very potent threat), or else simply break through on the queenside while White is occupied elsewhere.
As his opponent will often be looking to play
e4-e5, Black should usually put some effort into preventing this move, either by pressuring the
d5 pawn or (more usually) by contesting
e5 itself, taking advantage of the half-open file against White's pawn on
e4 (in lines where White plays
f2-f4, this pawn is even backwards, making it even more of a target). Black normally castles kingside and plays
...Re8 relatively early to assist in this endeavor.
White's d-pawn is a bit of a thorn in Black's position, making it sometimes unclear where Black should place his queenside minor pieces. Black's Queen-Knight often develops to
d7 and eventually to
e5, to blockade White's
e4-e5 advance, but sometimes instead Black can play
...Nb8-a6-c7 to put some pressure on
d5 and support a
b7-b5 advance, or this Knight may land on a
b4 outpost after White has played
a2-a4. Black's Queen Bishop usually gets played either to
g4 (and then is often traded for a White Knight on
f3 to make
e4-e5 more difficult), or to
d7 to support the queenside attack.
Of course, kingside action is not at all out of the question for Black; the half-open e-file gives him some good options on that side of the board as well. In particular, Black's powerful Bishop on the long diagonal constantly threatens to slide into a very strong outpost on
d4, and Black's Knights often land on the kingside anyway in the course of natural development.
[White "Kalju Vark"]
[Black "Mikhail Tal"]
[FEN "r1b1r1k1/pp1nq1bp/3p2p1/2pP1p2/1nB1PP2/P1N1BNP1/1P2QK1P/R6R b - - 0 1"]
1...fxe4! 2.Ng5 Nd3+! 3.Kg2 Nf6 4.Ba2 Bg4 5.Qd2 h6 6.h3