I have somewhere promised an overview and comparison of the so-called Queen's Pawn Openings (also known as D-pawn Specials or even D-pawn Deviations). That is basically all White's alternatives to the Queen's Gambit and the Catalan. In this first part I will only give a list and some brief comments.
Group IA: 1.d4 d5, alternatives to 2.Nf3 and 2.c4
1...d5 is an older move than 1...Nf6, so this is the classical starting position for the Queen's Pawn Openings. By deviating at this early point White makes sure that the game will be played on his homeground.
a) 2.g3?! - A poor relative of the Catalan. Black can equalize by an early ...c6 and ...Bf5.
b) 2.e3 - Introduces the Stonewall Attack (Bd3+f4+c3). A critical line is 2...Nf6 3.Bd3 Nc6.
c) 2.Bf4!? - The Neo-London. By some experts considered to revitalize the classical London system.
d) 2.Bg5!? - The Hodgson Opening. Frequently used as a companion system to the Trompowsky.
e) 2.e4?! - The Blackmar Diemer Gambit (BDG). Not entirely correct but many prefers to decline the pawn offer with 2...e6 (French) or 2...c6 (Caro Kann).
f) 2.Nc3!? - Normally leads to the Veresov Opening after 2...Nf6 3.Bg5 but 2...Bf5 may be best.
g) 2.a3!? - The Prie Opening. White argues that 2...c5 is too risky and all D-Pawn Specials are inferior (the more so a move down).
h) 2.c3?! - A sly but slow move which may lead to the Colle, the London or the Torre. 2...Nf6 followed by 3...Bf5 should equalize.
i) 2.Nd2 - Normally leads to some kind of Colle after 2...Nf6 3.e3.
j) 2.b3 - May lead to a Colle Zukertort but I cannot see how White can benefit from delaying e3 and Nf3.
k) 2.h3?! - A joke move favoured by some London players who will follow up with Bf4 and reach an only slightly inferior London.
l) 2.f4?! - A too primitive attempt to play the Stonewall Attack. 2...Nf6 followed by 3...Bf5 at least equalizes.
Group IB: 1.d4 d5 2.Nf3 Nf6, alternatives to 3.c4 and 3.e3
2.Nf3 is a sound and flexible move and the starting point of most Queen's Pawn openings. Black has a few interesting alternatives to 2...Nf6, such as 2...c5 and 2...Bf5!? but most alternatives, including 2...c6 and 2...e6 allow White to go ahead with his planned set-up.
a) 3.g3?! - An inferior version of the Catalan 3...Bf5 or 3...c6 followed by 4...Bf5 equalizes.
b) 3.Bg5?! - An inferior version of the Torre. 3...Ne4 equalizes.
c) 3.Bf4 - The classical London System. 3...c5 4.e3 Nc6 5.c3 Qb6 6.Qb3 c4 7.Qc2 Bf5 is probably equal.
d) 3.Nbd2 - A rare path to the Colle. 3...Bf5 probably equalizes.
e) 3.c3!? - Lakdawala's path to the London. The idea is to meet 3...c5 with 4.dxc5 and most other moves with 4.Bf4.
f) 3.Ne5 - A possibly underestimated attempt to reach a Stonewall Attack (with f4. White hopes to fight for an advantage after 3...Bf5 4.c4.
g) 3.a3 - A version of the Prie System.
h) 3.b3?! - Usually an attempt to reach the Colle Zukertort system. 3...Bf5 equalizes comfortably.
i) 3.Nc3 - Looks similar to the Barry Attack but is rather pointless as long as Black hasn't played ...g6.
j) 3.h3?! - Normally another way to reach a slightly inferior London system after a delayed Bf4.
Group IC: 1.d4 d5 2.Nf3 Nf6 3.e3 c5, alternatives to 4.c4
After 3.e3 we are in Colle territory, and might reasonably stop at that, noting that 4.c4 would still be a (harmless) Queen's Gambit. However, the Colle comes in different flavours too:
a) 4.dxc5 - This is an attempt to play the Queen's Gambit accepted a tempo up but 4...e6 probably gives theoretical equality.
b) 4.b3 - This is not White's most promising variation of the Colle Zukertort. After 4...Nc6 5.Bb2 Bg4 Black is equal. Also Kaufman's 4...cxd4, taking advantage of the fact that Bc1 not can use two diagonals, makes sense.
c) 4.c3 - Heads for the (Classical) Koltanowski Colle. The interesting question is whether Black now should play the modest 4...e6 or the more ambitious 4...Nc6.
d) 4.Nbd2 - A seemingly sensible Colle move that isn't even mentioned in several works on the Colle.
e) 4.Bd3!? - A slightly provocative attempt to stop ...Bf5 and keep open both the b3 and c3 options. The critical reply of course is 4...c4!?
f) 4.a3!? - An attempt to reverse colours - perhaps planning dxc5 followed by b4 and c4. But is a3 really useful after 4...cxd4 5.exd4?
g) 4.Ne5 - White intends to follow up with f4, Bd3 and c3, reaching a Stonewall Attack.
Group ID: 1.d4 d5 2.Nf3 Nf6 3.e3 e6, alternatives to 4.c4
This is the traditional starting position of the Colle. It should be noted that this position is at least as likely to appear from the move-order 1.d4 Nf6 2.Nf3 e6 3.e3 d5. White can still return to lines of the Queen's Gambit with 4.c4 but within the Colle there are these options:
a) 4.Be2 - A reversed Queen's Gambit Declined. Solid for Black but unambitious for White.
b) 4.b3 - Reveals White's plan to play a Colle Zukertort earlier than necessary.
c) 4.c3 - Reveals White's plan to play a Colle Koltanowski earlier than necessary.
d) 4.a3 - Attempts to play a Queen's Gambit Accepted a tempo or two up after 4...c5 5.dxc5 Bxc5 6.b4 but that's hardly sufficient for an advantage.
e) 4.Ne5 - White intends to follow up with f4, Bd3 and c3, reaching a Stonewall Attack. Probably more promising with Black's light-squared bishop locked in than the 3...c5 version.
f) 4.Nbd2!? - A seemingly sensible Colle move that isn't even mentioned in several works on the Colle.
g) After the main move 4.Bd3 and the extremely natural 4...c5 White has these options:
g1) 5.c4 - Still a Queen's Gambit (a rather harmless Tarrasch)
g2) 5.0–0 - A provocative attempt to keep options open. 5...c4 6.Be2 b5 is the critical line.
g3) 5.b3! - The Colle Zukertort, a legitimate try for an advantage even at GM level.
g4) 5.c3 - The Colle Koltanowski, actually a reversed Slav and quite dangerous for the unprepared.
Group IIA: 1.d4 Nf6, alternatives to 2.Nf3 and 2.c4
With his first move Black displays a less compromising attitude than 1...d5 does. This can be seen as a reason for White to avoid a theoretical confrontation. However, it must also be said that it is probably harder for White to fight for a real advantage without an early c4 if Black knows what he is doing.
a) 2.g3 - An inferior attempt to reach the Catalan. Black is equal after 2...d5 followed by ...c6 and ...Bf5.
b) 2.Bg5 - The Trompowsky. Now almost mainstream and occasinally tested at the highest level. White will frequently capture the f6 knight if that doubles Black's pawns but also setting up a Stonewall with pawns on c3, d4, e3 and f4 makes sense.
c) 2.c3 - Extremely flexible and extremely tame. One idea is to meet 2...g6 as well as 2...e6 with 3.Bg5 (which both may be categorized as Trompowskys).
d) 2.Bf4 - A somewhat experimental branch of the Neo London. 2...c5 and 2...d6 must be the critical lines.
e) 2.Nc3 - After 2...d5, 3.Bg5 is the Veresov Attack. Not very popular for the moment but that may be about to change.
f) 2.Nd2 - Used to be a favorite of Varga's. White to some extent threatens 3.e4 and after 2...d5 3.Nf3 we have a Colle (IBd).
g) 2.e3 - A possibly inferior version of the Stonewall Attack. 2...g6 is supposed to be strong but White can pretend he is playing a reversed French vs. King's Indian Attack.
h) 2.f4 - An ugly attempt to play the Stonewall Attack. 2...d5 followed by 3...Bf5 possibly is the simplest solution but also a plan including ...d6 and ...e5 looks tempting.
i) 2.g4 - The Gibbins-Weidenhagen Gambit. Almost certainly unsound but White has some practical chances after 2...Nxg4 3.e4.
j) 2.a3 - This attempt to reach a reversed QP opening doesn't make much sense after 2...g6.
k) 2.b3 - May lead to a Colle Zukertort but I cannot see how White can benefit from delaying e3 and Nf3.
l) 2.f3 - May lead to a Blackmar Diemer Gambit after 2...d5 3.e4 dxe4 4.Nc3. Probably 3...e6 is a simpler cure. 2...g6 3.e4 d6 is a Pirc.
m) 2.h3 - Looks rather pointless but if White follows up with Bf4 and Nf3 he will probably reach a playable London position.
Group IIB: 1.d4 Nf6 2.Nf3 e6, alternatives to 3.c4 and 3.g3
Nimzo- and Queen's Indian players may have a tougher task against the D-pawn Specials, (in particular the Colle) than others. Against this move-order the Colle Zukertort probably holds prospects for a small advantage.
a) 3.e3 - White heads for some branch of the Colle but may need other ideas against 3...b6 and 3...c5.
b) 3.Bg5 - The Torre System
c) 3.Bf4 - An important branch of the London System
d) 3.c3 - A tricky move, keeping open options to enter the Koltanowski Colle, the London or the Torre.
e) 3.Nbd2 - Possibly an underestimated branch of the Colle. Black must decide whether he considers e4 a threat or not.
f) 3.a3 - Another branch of the Prie System. White takes on Black's role with a marginally useful extra tempo.
g) 3.b3 - Heads for a Colle Zukertort but White gains nothing by revealing his plan too early.
h) 3.h3 - Another joke path to a playable if uninspiring London set-up.
i) 3.Nc3 - Looks similar to the Barry Attack but is rather pointless as long as Black hasn't played ...g6.
Group IIC: 1.d4 Nf6 2.Nf3 g6, alternatives to 3.c4 and 3.g3
The King's Indian is one of the toughest tests for any Queen's Pawn System. Black develops quickly and has various ways to challenge the centre. Lines with ...d6 followed by ...e5 or ...c5 probably are the most challenging but quieter lines with ...d5 are also available.
a) 3.e3?! - The Colle hasn't got a great reputation against the King's Indian, as Black can force ...e5 with relative ease. However, 3...Bg7 4.b4!? may well be OK for White.
b) 3.Bg5 - Purists will say that this isn't strictly speaking the Torre Attack. The Torre versus King's Indian (which it's sometimes called) probably is slightly less promising than the 2...e6 version.
c) 3.Bf4 - The third major branch of the London System.
d) 3.c3!? - Delays the decision of where (if?) to develop the dark-squared bishop but there is little to be gained as White will soon have to commit himself anyway after 3...Bg7 or 4...0-0.
e) 3.Nc3!? - introduces the Barry Attack after 3...d5 4.Bf4 (or a version of the 150-Attack after 3...Bg7 4.e4).
f) 3.Nbd2 - Heads for a Colle after 3...d5 4.e3 or a quiet Modern after 3...Bg7 4.e4.
g) 3.h3 - Once thought to be the most accurate move-order for White to play the London System against the King's Indian. However, the move is too slow to stop the ...Nfd7 and ...e5 plan.
h) 3.b3 - Has been played by Smyslov and Portisch but is mainly a modest way of getting the pieces out.
i) 3.b4!? - The Arkell System - at least if White keeps his c-pawn back and plays Nd2-c4, trying to restrain ...e5. I believe there is also a name for the more traditional approach with an early c4 but that line must belong to the King's Indian complex.
That's all folks! (well, I am sure I have forgotten something, so I expect to edit and update the overview)
The plan now is to take a closer look at some of the systems (mainly the Colle London and Torre), comparing them and perhaps suggest how some systems can be combined. I have also started collecting bibliographies.
Updated September 1st
I included some lines given by an anonymous reader.