# Chess Opening Theory/Great Big Opening Survey
## Introduction

This page is intended as an extended contents page of the Chess Opening Theory Wikibook project.
Not all openings are created equal. A 7th move variation in the Najdorf Sicilian needs its own page in this Wikibook. A 7th move variation in the Potato Variation of the Réti Opening does not.
But this is difficult to see when you're navigating through the book one move at a time starting from the initial position. One blue link looks the same as another. It's easy to get lost in the forest.
The rule for including an opening in the Great Big Opening Survey is simple:
Does your database have at least 100 games with this branch for every 50,000 games that start 1.e4?
In other words, take the number of 1.e4 games in the database and divide it by 500. That number is the cut-off for inclusion in this survey. (As this Wikibook grows, this cutoff can be lowered!)
The Opening Explorer at http://www.chessgames.com/perl/explorer, for example, has 396,710 1.e4 games as of 10th January 2018. So an opening line must appear in at least 396710 / 500 = 793 games in that database to be included.
Regardless of the size of your database, if you look at the frequency of White's initial moves this magic number should fall between 1.Nc3 and 1.b4 - between the unfashionable and the eccentric. If it falls below 1.b4, your database is probably not selective enough in what it considers high-level games. If it falls above 1.Nc3, your database might be out of date.
Because the Great Big Opening Survey is a very long list, an abridged version is shown, representing 10 times less "resolution", i.e. instead of appearing 100 times for every 50,000 1.e4 games, an opening must appear 1,000 times.
For every line given below, the last move that appears in the text is the last move that qualifies as an independent line under the above criteria. This move will be part of a bold blue link. Intermediate positions will be blue-linked but not bold.
Where a move is underlined, that move dips below the cut-off for inclusion but the resulting position does not, due to transpositions. Some lines have been extended beyond the cutoff, either to separate two lines that would otherwise appear to transpose into each other, or to merge two lines that were clearly converging on the same position.

## Abridged list (1,000 games per 50,000 1.e4 games)
### 1.e4 (23 lines)

* Sicilian Defence: 1...c5, then
** Open Sicilian: 2.Nf3 (alternatively Closed Sicilian: 2.Nc3 Nc6; Alapin Sicilian: 2.c3), then
*** Najdorf & Dragon Sicilians: 2...d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 then [A] Najdorf Sicilian: 5...a6; [B] Dragon Sicilian: 5...g6. For 5...Nc6 see 2...Nc6 > Classical Sicilian
*** 2...Nc6 3.d4 (alternatively Rossolimo Sicilian: 3.Bb5) 3...cxd4 4.Nxd4 Nf6 (for 4...e6 see 2...e6 > Taimanov Sicilian) then Classical Sicilian: 5.Nc3 d6
*** Taimanov & Kan Sicilians: 2...e6 3.d4 cxd4 4.Nxd4 then [A] Taimanov Sicilian: 4...Nc6 5.Nc3; [B] Kan Sicilian: 4...a6
* Open Game: 1...e5 2.Nf3 (alternatively King's Gambit: 2.f4), then
** 2...Nc6 (alternatively Petroff's Defence: 2...Nf6), then
*** Ruy Lopez: 3.Bb5, then
**** Closed Ruy Lopez: 3...a6 4.Ba4 Nf6 5.O-O Be7 6.Re1 b5 7.Bb3 d6 8.c3 O-O 9.h3
**** Berlin Defence: 3...Nf6
*** Italian Game: 3.Bc4, then
**** Two Knights: 3...Nf6
**** Giuoco Piano: 3...Bc5
*** Scotch Game: 3.d4 exd4
* French Defence: 1...e6 2.d4 d5 3.Nc3 (alternatively Tarrasch Variation: 3.Nd2), then [A] Winawer Variation: 3...Bb4; [B] Classical French: 3...Nf6
* Caro-Kann 1...c6 2.d4 d5
* Pirc Defence: 1...d6 2.d4 Nf6 3.Nc3
* Modern Defence: 1...g6 2.d4 Bg7 3.Nc3
* Scandinavian Defence: 1...d5 2.exd5
* Alekhine's Defence: 1...Nf6 2.e5 Nd5

### 1.d4 (9 lines)

* Indian Defences: 1...Nf6 2.c4 (or 2.Nf3 followed by 3.c4. For 2.Nf3 d5 see 1.d4 d5), then
** 2...e6, then
*** Queen's Indian Defence: 3.Nf3 b6 (for 3...d5 see Queen's Gambit Declined) 4.g3
*** Nimzo-Indian Defence: 3.Nc3 Bb4 (for 3...d5 see Queen's Gambit Declined), then [A] Rubinstein System: 4.e3; [B] Classical Variation: 4.Qc2
** 2...g6 3.Nc3, then
*** Grünfeld Defence: 3...d5
*** King's Indian Defence: 3...Bg7 4.e4 d6 5.Nf3 O-O 6.Be2 e5
** Benoni Defence: 2...c5 3.d5
* 1...d5 then Queen's Gambit: 2.c4 (or 2.Nf3 Nf6 3.c4), then
** Queen's Gambit Declined, Orthodox Defence: 2...e6 3.Nf3 Nf6 4.Nc3 (or 3.Nc3 Nf6 4.Nf3) 4...Be7 (for 4...c6 see Semi-Slav Defence)
** Slav Defence: 2...c6 3.Nc3 Nf6 4.Nf3 (or 3.Nf3 Nf6 4.Nc3) 4...e6 5. e3 5... Nbd7
* (For 1...e6 2.e4 see 1.e4 > French Defence; for 1...e6 2.c4 d5 see 1.d4 d5; for 1...e6 2.c4 Nf6 see 1.d4 Nf6)
* Dutch Defence: 1...f5

### 1.Nf3 (1 line)

* 1...Nf6 (for 1...c5 2.c4 see 1.c4 > Symmetrical English; for 1...c5 2.e4 see 1.e4 > Sicilian Defence; for 1...d5 2.d4 see 1.d4 > Queen's Gambit), then
** Barcza System: 2.g3 (for 2.c4 g6 3.d4 and 2.c4 e6 3.d4 see 1.d4 > Indian Defences)

### English Opening: 1.c4 (2 lines)

* Reversed Sicilian: 1...e5 2.Nc3 Nf6
* Symmetrical English: 1...c5 2.Nf3
* (for 1...Nf6 2.d4 see 1.d4 > Indian Defences; for 1...Nf6 2.Nc3 e5 see Reversed Sicilian; for 1...Nf6 2.Nf3 see 1.Nf3)
* (for Anglo-French: 1...e6 2.d4 - see 1.d4)

## Full list (100 games per 50,000 1.e4 games)

Abbreviations used below:
NSE = Not significant enough
NIE = Not independent enough. This indicates a line that appears to be above the cutoff, but would fall below it if subsequent transpositions were taken out.
alt. = Alternative, used to indicate an independent sideline
l/o = leaving out. This is a variation characterised by the leaving out of a move that appears in the main line. The variation is independent as long as the move left out is left out. If it gets played later, it may transpose back to the main line.
r/o = reserving option of.
[Pa-11] - these are Pachinko Index codes, developed specially for this Wikibook.

### 1.e4
#### Sicilian Defence 1.e4 c5, then

* [Si] Open Sicilian 2.Nf3, then
** [Si-11] O'Kelly Variation: 2...a6 l/o both Nc3, for which see St. George Sicilian 2.Nc3 a6 3.Nf3, and d4 for which see Najdorf, Taimanov or Kan lines
** [Si-13] Nimzowitsch Variation: 2...Nf6 bifurcates into 3.e5 and 3.Nc3
** (Hyper-Accelerated Dragon: 2...g6 3.d4 Bg7 is NIE due to 4.Nc3 cxd4 transposing to regular Accelerated Dragon. Independent line 4.dxc5 is NSE.)
** 2...d6, then
*** Moscow Variation: 3.Bb5+ Bd7 (alternatively [Si-14] 3...Nd7 4.d4; for 3...Nc6 see Rossolimo Variation 3...d6) 4.Bxd7+ Qxd7 5.O-O (alternatively [Si-15] Sokolsky Variation: 5.c4) [Si-16]5...Nc6
*** [Si-17] Basman-Palatnik Gambit: 3.c3 Nf6 4.Be2
*** (For 3.Nc3 see 3.d4 after 3...Nc6/3...Nf6 4.d4)
*** 3.d4 cxd4 4.Nxd4 (alt. [Si-18] Chekhover Variation: 4.Qxd4 Nc6 5.Bb5 Bd7 6.Bxc6 Bxc6 7.Nc3) 4...Nf6 5.Nc3 (alt. [Si-19] Prins Variation: 5.f3 l/o Nc3 r/o c4) (also arises via 3...Nf6 4.Nc3 cxd4 5.Nxd4), then
**** Najdorf: 5...a6, then
***** [Si-21] Modern Main Line: 6.Be3 6...e5 (for 6...e6 see Scheveningen, English Attack) 7.Nb3 Be6 8.f3 Be7 9.Qd2
***** 6.Bg5 e6 7.f4, then [Si-23] Old Main Line: 7...Be7 8.Qf3 Qc7 9.O-O-O; [Si-24] Poisoned Pawn: 7...Qb6
***** [Si-25] Opocensky Variation: 6.Be2 e5 (for 6...e6 see Scheveningen, Main Line) 7.Nb3 Be7 8. O-O O-O
***** [Si-26] Sozin-Najdorf: 6.Bc4 e6 7.Bb3 b5
***** [Si-27] Amsterdam Variation: 6.f4
***** [Si-28] Zagreb Attack: 6.g3
***** [Si-29] Adams Attack: 6.h3
***** (For 6.f3 see 6.Be3, Modern Main Line after 6...e5 7.Nb3 Be6 8.Be3 Be7 9.Qd2 or Scheveningen, English Attack after 6...e6 7.Be3)
**** Dragon: 5...g6, then Yugoslav Attack: 6.Be3 (alternatively [Si-31] Alekhine Variation: 6.Be2 Bg7 7.O-O) 6...Bg7 7.f3 O-O 8.Qd2 Nc6 (or 7...Nc6 8.Qd2 O-O), then [Si-35] B78/B79: 9.Bc4 Bd7 10.O-O-O; [Si-39] 9.O-O-O d5
**** Classical: 5...Nc6, then
***** Richter-Rauzer: 6.Bg5 e6 (alternatively [Si-41] Larsen Variation: 6...Bd7 r/o ...Rc8) 7.Qd2 7...a6 (alternatively [Si-42] B64/65: 7...Be7 8.O-O-O O-O) 8.O-O-O then [Si-43] B68/69: 8...Bd7 9.f4; [Si-45] B66: 8...h6
***** Sozin: 6.Bc4 then [Si-47] Sozin-Scheveningen: 6...e6 7.Be3; [Si-48] Benko Variation: 6...Qb6
***** [Si-49] Boleslavsky Variation: 6.Be2 e5
**** Scheveningen: 5...e6, then [Si-51] Main Line: 6.Be2 Be7 7.O-O; [Si-55] Keres Attack: 6.g4 h6; [Si-59] English Attack: 6.Be3 a6 7.f3 b5
** 2...Nc6, then
*** Rossolimo Variation: 3.Bb5, then
**** 3...g6, then [Si-61] White tries to play d4: 4.O-O Bg7 5.Re1 (or 5.c3 Nf6 6.Re1); [Si-64] White settles for d3: 4.Bxc6 dxc6 5.d3
**** [Si-66] 3...d6 4.O-O Bd7 5.Re1 Nf6 6.c3 a6
**** [Si-68] 3...e6 4.O-O Nge7
*** (For 3.Nc3 see Accelerated Dragon after 3...g6 4.d4 cxd4 5.Nxd4, 2...e6 after 3...e6, or 2...d6 after 3...d6 4.d4 cxd4 5.Nxd4 Nf6)
*** (For 3.c3 see Alapin Sicilian)
*** 3.d4 cxd4 4.Nxd4, then
**** 4...Nf6 5.Nc3 then Pelikan Variation: 5...e5 (for 5...d6 see 2...d6; for 5...e6 see Taimanov Four Knights) 6.Ndb5 d6 7.Bg5 a6 8.Na3 b5, then
***** [Si-71] Chelyabinsk Variation: 9.Nd5 Be7 10.Bxf6 Bxf6 11.c3 O-O 12.Nc2
***** 9.Bxf6 gxf6 10.Nd5 then [Si-72] Sveshnikov Variation: 10...f5; [Si-73] 10...Bg7
**** Accelerated Dragon: 4...g6, then Maroczy Bind: 5.c4 (alternatively [Si-74] B35 Variation: 5.Nc3 Bg7 6.Be3 Nf6 7.Bc4 O-O 8.Bb3), then
***** [Si-75] Breyer Variation: 5...Bg7 6.Be3 Nf6 7.Nc3 O-O 8.Be2 (can also arise via 5...Nf6 6.Nc3 d6 7.Be2) 8...d6 9.O-O Bd7
***** [Si-76] Gurgenidze Variation: 5...Nf6 6.Nc3 d6 7.Be2 Nxd4 8.Qxd4 Bg7
**** (For 4...e6 see Taimanov Variation)
**** Löwenthal Variation: 4...e5 5.Nb5 then [Si-77] Kalashnikov Variation: 5...d6 6.N1c3 (alternatively [Si-78] Kalashnikov Maroczy Bind: 6.c4) 6...a6 7.Na3 - lines where Black doesn't transpose to the Sveshnikov with ...b5 and ...Nf6
**** (For Flohr Variation: 4...Qc7 5.Nc3 e6 see Taimanov, Bastrikov Variation)
**** [Si-79] Grivas Variation: 4...Qb6 5.Nb3 Nf6 6.Nc3 e6
** 2...e6, then
*** 3.d4 cxd4 4.Nxd4, then
**** Taimanov Variation: 4...Nc6 5.Nc3 (alt. [Si-81] Szen Variation: 5.Nb5 d6 6.c4), then Bastrikov Variation: 5...Qc7 (for 5...Nf6 6.Ndb5 d6 7.Bf4 e5 8.Bg5 - see Pelikan Variation; for 5...d6 6.Be3 Nf6 see Scheveningen Variation), then
***** [Si-83] 6.g3 a6 7.Bg2 Nf6 8.O-O
***** [Si-85] 6.Be2 a6 (or 5...a6 6.Be2 Qc7) 7.O-O Nf6 8.Be3 (or 6.Be3 a6 7.Be2 Nf6 8.O-O) 8...Bb4
***** B48: 6.Be3 a6 then [Si-87] 7.Bd3 Nf6 8.O-O; [Si-89] 7.Qd2 Nf6 8.O-O-O (for 7.Be2 see 6.Be2)
**** Kan Variation: 4...a6, l/o ...Nc6 - although Black typically reserves the option of ...Nc6, so the real difference between the Kan and Taimanov is in the different options they give White - Nbd5 in the case of the Taimanov, Bd3 in the case of the Kan. Then
***** 5.Bd3, then [Si-91] 5...Nf6 6.O-O Qc7; [Si-93] Polugayevsky Variation: 5...Bc5 6.Nb3 Be7 (6...Ba7 is the other independent line that's under the cutoff)
***** [Si-95] B43: 5.Nc3 Qc7 (alt. [Si-97] 5...b5 6.Bd3; for 5...Nc6 see Taimanov Variation) 6.Bd3 (for 6.Be2 Nc6 see Taimanov Variation) 6...Nf6
***** [Si-99] Bronstein Variation: 5.c4 Nf6 6.Nc3
**** (For 4...Nf6 5.Nc3 see Sveshnikov Variation after either 5...Nc6 6.Ndb5 d6 7.Bf4 e5 or 5...d6)
*** (For 3.Nc3 see Kan Variation after 3...a6 4.d4 or Taimanov Variation after 3...Nc6 4.d4)
*** (For 3.c3 see Alapin Variation after either 3...d5 4.exd5 Qxd5 5.d4 or 3...Nf6 4.e5 Nd5 5.d4)
*** (Kramnik Variation: 3.c4 is NIE due to transpositions to c4 lines of the Taimanov after a subsequent d4)
*** King's Indian Attack, ...e6 Defence: 3.d3 Nc6 4.g3 g6 5.Bg2 Bg7 6.O-O Nge7 - go to King's Indian Attack Island
*** (for 3.b3 - see Czerniak Variation)
* [As] Anti-Sicilians: 1.e4 c5 everything other than Nf3
** Closed Sicilian 2.Nc3 l/o d4 where Black r/o preventing d4 with ...g6, ...Bg7 and ...Nd4, then
*** 2...Nc6, then
**** King's Indian Attack Sicilian: 3.g3 g6 4.Bg2 Bg7 5.d3 d6 6.f4 (6.Be3 lines where White avoids f4 are NIE due to transposition to King's Indian Attack, ...e6 Defence) 6...e6 7.Nf3 Nge7 8.O-O O-O 9.Be3 - go to King's Indian Attack Island
**** [As-11] Grand Prix Attack (A): 3.f4 l/o g3 r/o Bc4 or Bb5, then 3...g6 4.Nf3 Bg7 5.Bb5 Nd4 - lines where White doesn't save the bishop with 6.Bc4
**** [As-19] 3.Bb5 Nd4 4.Bc4
**** (For Chameleon Variation: 3.Nge2 see the equivalent 2.Nf3 line if White follows up with d4, or the King's Indian Attack if White follows up with g3 and d3)
**** (For 3.Nf3 see Open Sicilian 2.Nf3)
*** (For 2...e6 3.Nf3 - see Open Sicilian 2.Nf3)
*** 2...d6 then [As-15] Grand Prix Attack (B): 3.f4 l/o g3 r/o Bc4 or Bb5 for White, l/o ...Nc6 for Black (for 3.Nf3 see Open Sicilian 2.Nf3; for 3.g3 see King's Indian Attack)
*** [As-21] St. George Sicilian: 2...a6 where White avoids d4 transposing to an Open Sicilian
** Alapin Sicilian 2.c3, then
*** Main Line: 2...Nf6 3.e5 3...Nd5, then
**** Lines with ...d6 and ...e6: [As-31] 4.d4 cxd4 5.Nf3 e6 6.cxd4 d6 (can arise via 4.Nf3)
**** Lines with ...d6 and ...Nc6: [As-39] 4.d4 cxd4 5.Nf3 Nc6 6.cxd4 d6 7.Bc4 Nb6
*** Barmen Variation: 2...d5 3.exd5 Qxd5 4.d4, then
**** [As-41] Black shuts in the bishop: 4...Nf6 5.Nf3 e6
**** [As-49] Black puts the bishop on g4: 4...Nc6 5.Nf3 Bg4 followed by ...Nf6, or 4...Nf6 5.Nf3 Bg4 followed by ...Nc6
*** (for 2...e6 3.d4 (for 3.Nf3 see 2.Nf3) 3...d5 see French Advance after 4.e5 or French Tarrasch with 9.c3 after 4.exd5)
*** (for 2...d6 3.Nf3 see Open Sicilian 2.Nf3)
** [As-51] Smith-Morra Gambit: 2.d4 cxd4 3.c3 l/o Ng1-f3-xd4
** [As-61] McDonnell Attack: 2.f4 bifurcates into ...Nc6 lines where White avoids Nc3 transposing to the Closed Grand Prix, and the Tal Defence 2...d5
** [As-71] Czerniak Variation: 2.b3
** (For Keres Variation: 2.Ne2 Nc6 - see Open Sicilian after 3.d4 cxd4 4.Nxd4 or Chameleon Variation after 3.Nbc3)
** (For 2.d3 Nc6 3.g3 see Closed Sicilian for lines where White plays Nc3 at some point, or McDonnell Attack for lines where White plays f4 at some point)

#### [Kp] Mutual King's Pawn: 1.e4 e5, then

(This is highly dependent on what years your database covers. Many of the following alternatives to the Ruy Lopez show up in databases of "historic" games far more than in current master play.)
* Vienna Game: 2.Nc3 l/o c4, then 2...Nf6 (for 2...Nc6 see Spanish Four Knights after 3.Nf3 or Bishop's Opening after 3.Bf4), then
** (for 3.Nf3 Nc6 see Four Knights)
** [Kp-11] Vienna Gambit: 3.f4 d5 4.fxe5 Nxe4
** [Kp-19] Smyslov Variation: 3.g3
** (for 3.Bc4 Nc6 4.d3 see Bishop's Opening)
* King's Gambit: 2.f4, then
** King's Gambit Accepted: 2...exf4 then [Kp-21] King's Knight Gambit: 3.Nf3 g5, [Kp-23] King's Bishop Gambit: 3.Bc4
** [Kp-26] Falkbeer Counter-Gambit: 2...d5 3.exd5
** [Kp-28] King's Gambit Declined: 2...Bc5 3.Nf3 d6
* [Kp-31] Bishop's Opening: 2.Bc4 Nf6 3.Nc3 (for 3.d3 Nc6 4.Nf3 see Two Knights) 3...Nc6 4.d3
* (Centre Game: 2.d4 exd4 is NIE due to transpositions to Scotch and Philidor. Centre Game lines 3.c3 and 3.Qxd4 are NSE. [Kp-4] is reserved for them anyway)
* 2.Nf3, then
** Petroff's Defence: 2...Nf6 then
*** Classical Petroff: 3.Nxe5 d6 4.Nf3 Nxe4 then [Kp-51] Jaenisch Attack: 5.d4 d5 6.Bd3 Nc6 7.O-O Be7 8.c4; [Kp-55] Nimzowitsch Attack: 5.Nc3
*** [Kp-59] Modern Attack: 3.d4 Nxe4 4.Bd3 d5 5.Nxe5
*** (for 3.Nc3 Nc6 see Four Knights)
** [Kp-61] Philidor's Defence: 2...d6 3.d4 exd4 4.Nxd4 Nf6 5.Nc3 Be7
** Hanham Defence: This is included as an independent position that can arise from several 1.e4 lines, without being a significant variation of any of them. [Kp-69] 1.e4 e5 2.Nf3 d6 3.d4 Nf6 4.Nc3 Nbd7 5.Bc4 Be7 6.O-O c6 is one possibility.
** 2...Nc6, then
*** Spanish Four Knights: 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.Bb5 (for 4.d4 exd4 5.Nxd4 see Scotch Four Knights) then [Kp-71] Symmetrical Spanish: 4...Bb4 5.O-O O-O 6.d3 d6; [Kp-75] Rubinstein Countergambit: 4...Nd4
*** [Kp-79] Ponziani Opening: 3.c3 l/o any move of the f1-bishop, which prevents White defending e4 with O-O and Re1, hence bifurcates into 3...d5 and 3...Nf6
*** (Special note - the Max Lange Attack is an independent position that can arise from several 2.Nf3 lines, but it's not a significant variation of any of them)
*** Italian Game: 3.Bc4, then
**** Two Knights Defence: 3...Nf6
***** [Kp-81] Open Variation: 4.d4 exd4 5.e5
***** [Kp-83] Old Main Line: 4.Ng5 d5 5.exd5 Na5 6.Bb5 c6 7.dxc6 bxc6 8.dxe5
***** [Kp-84] Modern Bishop's Opening: 4.d3 Be7 (for 4...Bc5 5.c3 d6 6.O-O or 5.O-O d6 6.c3 see Giuoco Pianissimo) 5.O-O O-O
**** 3...Bc5, then
***** Giuoco Piano: 4.c3 Nf6, then
****** [Kp-85] Main Line: 5.d4 exd4 6.cxd4 Bb4
****** [Kp-87] Giuoco Pianissimo: 5.d3 - White plays Bb3, O-O and Nbd2, Black plays ...d6, ...a6, ...Ba7 and ...O-O, with numerous move orders possible
***** [Kp-88] Evans Gambit: 4.b4 Bxb4 5.c3 Ba5
***** (For 4.d3 Nf6 or 4.O-O Nf6 5.d3 see Two Knights)
*** Scotch Game: 3.d4 exd4 4.Nxd4 (Goring Gambit: 4.c3 is NSE; for Scotch Gambit: 4.Bc4 Nf6 5.e5 and 4.Bc4 Bc5 5.c3 Nf6 see Two Knights) then
**** [Kp-91] Classical Scotch: 4...Bc5 5.Be3 (alt. [Kp-94] Intermezzo Variation: 5.Nxc6) 5...Qf6 6.c3 Nge7
**** 4...Nf6, then
***** [Kp-96] Mieses Variation: 5.Nxc6 bxc6 6.e5 Qe7 7.Qe2 Nd5 8.c4
***** [Kp-99] Scotch Four Knights: 5.Nc3 Bb4 6.Nxc6 bxc6 7.Bd3 d5 8.exd5 cxd5 9.O-O O-O 10.Bg5 c6
*** [Ru] Ruy Lopez: 3.Bb5, then
**** Berlin Defence: 3...Nf6, then
***** Open Berlin: 4.O-O Nxe4 then [Ru-11] Berlin Wall: 5.d4 (alt. [Ru-19] 5.Re1 Nd6) Nd6 6.Bxc6 dxc6 7.dxe5 Nf5 8.Qxd8+ Kxd8 9.Nc3
***** (for 4.Nc3 see Spanish Four Knights)
***** Closed Berlin: 4.d3 l/o ...a6 Ba4, then [Ru-21] 4...d6 l/o Bb4 which makes no sense anyway; [Ru-29] 4...Bc5
**** [Ru-31] Schliemann Defence: 3...f5 4.Nc3
**** (Cordel (Classical) Defence: 3...Bc5 is NIE due to transpositions to Berlin and Møller. [Ru-4] reserved for it anyway)
**** Morphy Defence: 3...a6 4.Ba4 (alt. [Ru-51] Exchange Variation: 4.Bxc6 dxc6 5.O-O f6 6.d4) then 4...Nf6 (alt. [Ru-59] Modern Steinitz Defence: 4...d6 5.c3 l/o ...Nf6 r/o ...f5), then
***** [Ru-61] Wormald Attack: 5.Qe2
***** [Ru-69] Anderssen Variation: 5.d3
***** 5.O-O, then
****** [Ru-71] Open Ruy Lopez: 5...Nxe4 6.d4 b5 7.Bb3 d5 8.dxe5 Be6
****** 5...b5 6.Bb3 then [Ru-74] Møller Defence: 6...Bc5 l/o ...Bb7; [Ru-76] Arkhangelsk Defence: 6...Bb7 (for 6...Be7 see Closed Ruy Lopez)
****** Closed Ruy Lopez: 5...Be7 6.Re1 (alt. [Ru-79] DERLD: 6.Bxc6 dxc6; for 6.d3 b5 7.Bb3 see Anderssen Variation) 6...b5 7.Bb3 (or 5...b5 6.Bb3 Be7 7.O-O), then
******* Closed Main Line: 7...d6 8.c3 O-O 9.h3 (alt. [Ru-81] Bogoljubow Variation: 9.d4 Bg4), then
******** [Ru-84] Chigorin Variation: 9...Na5 10.Bc2 c5 11.d4 Qc7 12.Nbd2
******** [Ru-86] Breyer Variation: 9...Nb8 10.d4 Nbd7 11.Nbd2 Bb7 12.Bc2 Re8 13.Nf1 Bf8 14.Ng3 g6
******** [Ru-88] Zaitsev Variation: 9...Bb7 10.d4 Re8 11.Nbd2 Bf8 l/o any move of the c6 knight
******* to Marshall Gambit: 7...O-O, then
******** 8.c3 then Marshall Gambit: 8...d5 (8...d6 - see Closed Main Line) [Ru-91] 9.exd5 Nxd5 10.Nxe5 Nxe5 11.Rxe5 c6 - included because it's the point of 7...O-O
******** (Anti-Marshall: 8.h3 is NIE due to transposition to Closed with 8...d6)
******** [Ru-99] Kasparov Attack: 8.a4

#### [Fr] French Defence: 1.e4 e6, then

* King's Indian Attack French: 2.d3 d5 3.Nd2 Nf6 4.Ngf3 - go to King's Indian Attack Island
* [Fr-11] 2.Nf3 d5 (for 2...c5 see Sicilian Defence) bifurcates into Two Knights Variation: 3.Nc3 Nf6 4.e5 Nd7 5.d4 and Wing Gambit: 3.e5 c5 4.b4
* [Fr-19] Chigorin Variation: 2.Qe2
* 2.d4 d5, then
** Tarrasch French: 3.Nd2, then
*** 3...c5 4.exd5, then [Fr-21] C08/09: 4...exd5 5.Ngf3 Nc6 6.Bb5 Bd6, [Fr-23] Chistyakov Defence: 4...Qxd5 5.Ngf3 cxd4 (or 4.Ngf3 cxd4 5.exd5 Qxd5) 6.Bc4 Qd6 7.O-O Nf6 8.Nb3 Nc6 9.Nbxd4 Nxd4 10.Nxd4
*** [Fr-26] Morozevich Variation: 3...Be7 bifurcates into 4.Ngf3 and 4.Bd3
*** (for 3...dxe4 4.Nxe4 see 3.Nc3, Rubinstein Variation)
*** [Fr-29] Guimard Variation: 3...Nc6 4.Ngf3 Nf6 5.e5 Nd7
*** Closed Tarrasch: 3...Nf6 4.e5 Nfd7, then
**** [Fr-31] Botvinnik Variation: 5.Bd3 c5 6.c3 (or 5.c3 c5 6.Bd3) 6...Nc6 7.Ne2 cxd4 8.cxd4 f6 9.exf6 Nxf6 10.O-O (or 10.Nf3 Bd6 11.O-O)
**** [Fr-39] 5.f4 c5 6.c3 (or 5.c3 c5 6.f4) 6...Nc6 7.Ndf3
** Advance French: 3.e5 c5 4.c3 Nc6 5.Nf3 then [Fr-41] 5...Qb6 (or 4...Qb6 5.Nf3 Nc6) 6.a3, [Fr-49] 5...Bd7 6.Be2
** Exchange French: 3.exd5 l/o Nc3, 3...exd5 then [Fr-51] 4.Bd3, [Fr-59] 4.Nf3
** 3.Nc3, then
*** Winawer: 3...Bb4, then
**** Advance Winawer: 4.e5 c5 5.a3 Bxc3 6.bxc3 Ne7 (or 4...Ne7 5.a3 Bxc3+ 6.bxc3 c5), then [Fr-61] Poisoned Pawn Winawer: 7.Qg4, [Fr-64] 7.Nf3
**** [Fr-66] Exchange Winawer: 4.exd5 exd5 5.Bd3
**** [Fr-68] Alekhine Gambit: 4.Nge2
*** 3...Nf6, then
**** 4.Bg5, then
***** [Fr-71] Burn Variation: 4...dxe4 5.Nxe4 Be7 6.Bxf6
***** [Fr-75] Classical French: 4...Be7 5.e5 Nfd7 6.Bxe7 Qxe7
***** [Fr-79] MacCutcheon Variation: 4...Bb4 5.e5 h6 6.Bd2 Bxc3
**** Steinitz French, Boleslavsky Variation: 4.e5 Nfd7 5.f4 c5 6.Nf3 Nc6 7.Be3, then
***** Lines where White captures on c5: [Fr-81] 7...a6 8.Qd2
***** Lines where Black captures on d4: [Fr-89] 7...cxd4 8.Nxd4
*** [Fr-91] Rubinstein French: 3...dxe4 4.Nxe4 Nd7 (alt. [Fr-99] Fort Knox Variation: 4...Bd7 5.Nf3 Bc6 6.Bd3) 5.Nf3 Ngf6 6.Nxf6 (for 6.Bg5 see 4.Bg5, Burn Variation) 6...Nxf6

#### [Ks] 1.e4 - everything else:

* Caro-Kann Defence: 1.e4 c6, then
** [Ks-11] English Variation: 2.c4 d5 3.exd5 cxd5 4.cxd5 Nf6
** [Ks-19] Two Knights Variation: 2.Nc3 d5 3.Nf3 Bg4 4.h3 Bxf3 5.Qxf3
** Breyer Variation (King's Indian Attack Caro-Kann): 2.d3 d5 3.Nd2 - go to King's Indian Attack Island
** 2.d4 d5, then
*** Exchange Caro-Kann: 3.exd5 cxd5, then
**** [Ks-21] Main Line: 4.Bd3 Nc6 5.c3
**** Panov-Botvinnik Attack: 4.c4 Nf6 5.Nc3, then
***** [Ks-23] 5...Nc6 bifurcates into 6.Bg5 and 6.Nf3
***** 5...e6 6.Nf3 then [Ks-26] 6...Be7; [Ks-28] 6...Bb4
*** Advance Caro-Kann: 3.e5 Bf5 (alt. [Ks-31] Arkell-Khenkin Variation 3...c5) then [Ks-35] Short Variation: 4.Nf3 e6 5.Be2; [Ks-39] Bayonet Attack: 4.Nc3 (Bayonet because the main line is 4...e6 5.g4 Bg6 6.Nge2)
*** 3.Nc3 dxe4 4.dxe4 OR 3.Nd2 dxe4 4.dxe4, then
**** [Ks-41] Classical Caro-Kann, Spassky Variation: 4...Bf5 5.Ng3 Bg6 6.h4 h6 7.Nf3 Nd7 (or 6.Nf3 Nd7 7.h4 h6) 8.h5 Bh7 9.Bd3 Bxd3 10.Qxd3 e6 bifurcates into 11.Bd2 and 11.Bc4;
**** Karpov Variation: 4...Nd7 then [Ks-43] 5.Ng5 (5...Ndf6 is the Ivanchuk Defence); [Ks-45] 5.Nf3 Ngf6 (6.Ng3 is the Kasparov Attack)
**** 4...Nf6 5.Nxf6 then [Ks-47] Bronstein-Larsen Variation: 5...gxf6; [Ks-49] Tartakower Variation: 5...exf6
* Pirc Defence: 1.e4 d6 2.d4 Nf6 (for 2...g6 see Modern Defence) 3.Nc3 l/o c4 compared to the King's Indian, which 3.f3 followed by c4 transposes to) then
** 3...g6, then
*** [Ks-51] Austrian Attack: 4.f4 Bg7 5.Nf3 O-O 6.Bd3
*** [Ks-53] Classical Pirc: 4.Nf3 Bg7 5.Be2 O-O 6.O-O c6
*** [Ks-54] 150 Attack: 4.Be3 c6 where White eventually puts the f1-bishop on d3 rather than transposing to the Classical or Czech with Be2
*** [Ks-56] Robert Byrne Attack: 4.Bg5
** [Ks-57] Queenswap: 3...e5 4.dxe5 (for 4.Nf3 Nbd7 and 3...Nbd7 4.Nf3 e5 see Hanham Defence) 4...dxe5 5.Qxd8 Kxd8
** [Ks-59] Czech Pirc: 3...c6 l/o ...g6
* Modern Defence: 1.e4 g6 2.d4 (for 2.Nf3 see Sicilian Defence after 2...c5 or Classical Pirc after 2...Bg7 3.d4 d6 4.Nc3 Nf6; for 2.Nc3 Bg7 3.g3 c5 (or 3...d6 4.Bg2 c5) see Sicilian Defence) 2...Bg7 (2...d6 transposes after 3.Nc3 Bg7 or 3.Nf3 Bg7), then
** 3.Nc3, then
*** 3...d6 4.Be3 (for 4.f4 Nf6 see Pirc, Austrian Attack; for 4.Nf3 Nf6 (or 3.Nf3 d6 4.Nc3 Nf6) see Classical Pirc) then [Ks-61] Tiger's Modern: 4...a6; [Ks-63] 4...c6 l/o...Nf6 transposing to a Pirc
*** [Ks-66] Gurgenidze Variation: 3...c6 4.Nf3 d5 also arises via Caro-Kann
** [Ks-68] Averbakh Variation: 3.c4 d6 4.Nc3 then Kotov Variation: 4...Nc6 l/o ...Nf6 r/o ...f5 (for 4...Nf6 see King's Indian Defence)
* [Ks-71] Scandinavian Defence: 1.e4 d5 2.exd5 Qxd5 (alt. [Ks-75] 2...Nf6 3.d4 Nxd5 bifurcates into 4.Nf3 and 4.c4) 3.Nc3 Qa5 (alt. [Ks-79] Tiviakov System: 3...Qd6 4.d4 Nf6 5.Nf3) 4.d4 White plays Bc4, Bd2 and Nf3, Black plays ...c6, ...Bf5, ...e6 and ...Nf6 in some order
* Alekhine's Defence: 1.e4 Nf6 2.e5 (alt. [Ks-81] Scandinavian Variation: 2.Nc3 d5 l/o ...e5 compared to the Vienna Gambit, r/o e5 by White) 2...Nd5 3.d4 d6, then
** Modern Alekhine: 4.Nf3 then [Ks-83] Main Line: 4...Bg4 5.Be2 e6; [Ks-86] Fianchetto Variation: 4...g6
** [Ks-88] Classical Alekhine: 4.c4 Nb6 (or 3.c4 Nb6 4.d4 d6) 5.exd6 bifurcates into 5...exd6 and 5...cxd6
* [Ks-91] Nimzowitsch Defence: 1.e4 Nc6 2.d4 (for 2.Nf3 e5 see 1...e5) bifurcates into 2...d5 and 2...e5
* [Ks-99] Owen's Defence: 1.e4 b6 2.d4 Bb7

#### [Ka] King's Indian Attack Island

There are many ways to reach King's Indian Attack Island. Most of the possible replies to 1.e4 have a King's Indian Attack variation of some sort. The lines found on King's Indian Attack Island have more in common with each other than with the openings they originated from.
* 1.e4 e6 then [Ka-1] King's Indian Attack French: 2.d3 d5 3.Nd2 Nf6 4.Ngf3
* 1.e4 c6 then [Ka-3] Breyer Variation (King's Indian Attack Caro-Kann): 2.d3 d5 3.Nd2
* 1.e4 c5 2.Nc3 Nc6 then [Ka-6] King's Indian Attack Closed Sicilian: 3.g3 g6 4.Bg2 Bg7 5.d3 d6 6.f4 (6.Be3 lines where White avoids f4 are NIE due to transposition to King's Indian Attack, ...e6 Defence) 6...e6 7.Nf3 Nge7 8.O-O O-O 9.Be3
* 1.e4 c5 2.Nf3 e6 then [Ka-7] King's Indian Attack Open (...e6) Sicilian: 3.d3 Nc6 4.g3 g6 5.Bg2 Bg7 6.O-O Nge7
* 1.Nf3 d5 then [Ka-9] King's Indian Attack, Yugoslav Defence: 2.g3 c6 (for 2...Nf6 see 1...Nf6) 3.Bg2 Bg4 (or 2...Bg4 3.Bg2 c6)

### 1.d4
#### [In] Indian Defences: 1.d4 Nf6, then

* Trompowsky Attack: 2.Bg5 then [In-11] 2...Ne4 3.Bf4 c5 4.f3, [In-13] 2...e6 3.e4 h6 4.Bxf6 Qxf6, [In-15] 2...d5 3.Bxf6
* 2.c4, then
** [In-17] Old Indian, Ukrainian Defence: 2...d6 l/o ...g6 which can be played any from move 3-6 to transpose to a King's Indian Defence, then 3.Nc3 (for 3.Nf3 g6 see King's Indian Defence) 3...e5 4.Nf3 (or 3.Nf3 Nbd7 4.Nc3) 4...Nbd7 5.e4 (Black and/or White can reverse the order of their last two moves)
** [In-19] Budapest Gambit: 2...e5 3.dxe5 Ng4
** (for Slav-Indian 2...c6 see 1...d5 after either 3.Nc3 d5 or 3.Nf3 d5)
** Nimzo-, Bogo- and Queen's Indian Defences: 2...e6, then
*** 3.Nc3 then Nimzo-Indian Defence: 3...Bb4 (for 3...d5 see 1...d5; for 3...c5 see Benoni/Benko), then
**** Rubinstein System: 4.e3, then
***** 4...O-O 5.Bd3 (alt. [In-21] Reshevsky Variation: 5.Nge2 d5 6.a3 Be7) 5...d5 6.Nf3 c5 (or 5...c5 6.Nf3 d5) 7.O-O then [In-23] Bernstein Variation: Nc6 8.a3 Bxc3 9.bxc3 Bxd3; [In-25] 7...dxc4 8.Bxc4 where Black avoids ...Nc6
***** [In-27] E42: 4...c5 5.Ne2 (for 5.Bd3 O-O or 5.Bd3 Nc6 6.Nf3 O-O see 4...O-O)
***** [In-29] Fischer Variation: 4...b6 5.Nge2
**** Classical Variation: 4.Qc2 then [In-31] Keres Defence: 4...O-O 5.a3 Bxc3 6.Qxc3 b6 7.Bg5 Bb7 bifurcates into 8.e3 and 8.f3; [In-33] Nimzo-Benoni: 4...c5 5.dxc5 O-O; [In-34] 4...d5 5.cxd5
**** Kasparov Variation: 4.Nf3 then [In-36] Nimzo-Queen's Indian: 4...b6 5.Bg5 Bb7 (4...c5 is NIE due to transpositions to 4.e3; 5.g3 is NSE. For 4...d5 see QGD Ragozin Variation)
**** [In-37] Kmoch Variation: 4.f3 d5 5.a3
**** (Sämisch Variation: 4.a3 Bxc3 5.bxc3 is NIE due to transpositions to 4.e3 lines)
**** Leningrad Variation: 4.Bg5 l/o Qc2 from Classical Variation, then [In-39] 4...c5 5.d5 h6 6.Bh4 (or 4...h6 5.Bh4 c5 6.d5)
*** 3.Nf3, then
**** Queen's Indian Defence: 3...b6 4.g3 Bb7 (alt. [In-41] Slipped Bishop Variation: 4...Ba6 5.b3 Bb4 6.Bd2 Be7 7.Bg2 c6) 5.Bg2, then
***** [In-42] Capablanca Variation: 5...Bb4+ 6.Bd2
***** Traditional Variation: 5...Be7 6.O-O O-O 7.Nc3 (or 6.Nc3 O-O 7.O-O) 7...Ne4 then [In-43] Old Main Line: 8.Qc2 Nxc3 9.Qxc3; [In-45] Classical Variation: 8.Bd2
**** Bogo-Indian Defence: 3...Bb4+ then
***** 4.Bd2 then [In-46] Nimzowitsch Variation: 4...Qe7 5.g3 Nc6; [In-47] 4...a5
***** (for 4.Nc3 see Nimzo-Indian Defence, Kasparov Variation)
***** Grünfeld Variation: 4.Nbd2 then [In-48] 4...O-O; [In-49] 4...b6
**** (for 3...c5 see English Anti-Benoni)
**** (for 3...d5 see 1...d5)
** King's Indian & Grünfeld Defences: 2...g6, then
*** 3.Nc3, then
**** King's Indian Defence: 3...Bg7 4.e4 (for 4.Nf3 see 3...d5 after 4...d5, or 4.e4 after either 4...d6 5.e4 or 4...O-O 5.e4) 4...d6, then
***** 5.Nf3 (or 4...O-O 5.Nf3 d6) 5...O-O 6.Be2 (alt. [In-51] 6.h3 e5 7.d5) 6...e5, then
****** 7.O-O, then
******* Mar del Plata Variation: 7...Nc6 8.d5 Ne7 then [In-52] Aronin Variation: 9.Ne1 Nd7, [In-53] Taimanov (Bayonet) Attack: 9.b4 Nh5, [In-54] Normal Variation: 9.Nd2
******* [In-55] Old Main Line: 7...Nbd7 (or 6...Nbd7 7.O-O e5) 8.Be3
******* [In-56] Glek Variation: 7...Na6 (or Kazakh Variation: 6...Na6 7.O-O e5)
****** [In-57] Gligoric Variation: 7.Be3 Ng4
****** [In-58] Petrosian System: 7.d5 a5
****** [In-59] Queenswap: 7.dxe5 dxe5 8.Qxd8 Rxd8 9.Bg5
***** Sämisch Variation: 5.f3 O-O 6.Be3 (alt. [In-61] 6.Bg5), then [In-62] Orthodox Sämisch: 6...e5; [In-64] Panno Variation: 6...Nc6 7.Nge2 a6
***** [In-65] Averbakh Variation: 5.Be2 O-O 6.Bg5 (for 6.Nf3 see 5.Nf3 O-O 6.Be2 e5, the difference between that and the Averbakh is the move ...e5 by Black)
***** (for Four Pawns Attack: 5.f4 O-O 6.Nf3 c5 7.d5 e6 8.Be2 exd5 9.cxd5 see Modern Benoni)
***** [In-67] Makagonov System: 5.h3 O-O 6.Bg5 (for 6.Nf3 see 5.Nf3 O-O 6.h3 e5 7.d5, the difference between that and the Makagonov is the move ...e5 by Black)
***** [In-69] 5.Bd3
**** Grünfeld Defence: 3...d5, then
***** Exchange Grünfeld: 4.cxd5 Nxd5 5.e4 Nxc3 6.bxc3 Bg7 then [In-71] Modern Exchange: 7.Nf3 (can also arise via 4.Nf3) 7...c5 8.Rb1 O-O 9.Be2, [In-73] Classical Exchange: 7.Bc4 c5 8.Ne2
***** Three Knights Grünfeld: 4.Nf3 Bg7 then [In-74] Russian Variation: 5.Qb3 dxc4 6.Qxc4 O-O 7.e4, [In-75] Petrosian Variation: 5.Bg5 Ne4 6.cxd5, [In-76] Burille Variation: 5.e3 O-O
***** [In-77] Brinckmann Attack: 4.Bf4 Bg7 5.e3 bifurcates into 5...O-O and 5...c5
***** [In-79] Stockholm Variation: 4.Bg5 l/o Nf3 (hence reacting to ...Ne4 by other means than defending the bishop with Nf3)
*** (for 3.Nf3 see 3.Nc3 after either 3...Bg7 4.Nc3 or 3...d6 4.Nc3, or Fianchetto King's Indian: 3.g3 after either 3...Bg7 4.g3 or 3...d6 4.g3)
*** Fianchetto King's Indian: 3.g3 Bg7 4.Nf3 (alt. [In-81] Neo-Grünfeld: 4.Bg2 d5 (for 4...O-O see 4.Nf3 after either 5.Nf3 or 5.Nc3 d6 6.Nf3)) 4...O-O 5.Bg2 d6 6.Nc3 (White and/or Black can reverse the order of their last two moves), then
**** [In-83] Panno Variation: 6...Nc6 7.O-O (or 6.O-O Nc6 7.Nc3) 7...a6
**** Classical Variation: 6...Nbd7 7.O-O (or 6.O-O Nbd7 7.Nc3) 7...e5 8.e4 then [In-85] 8...c6 9.h3; [In-87] 8...exd4 9.Nxd4
**** [In-89] Kavalek-Bronstein Variation: 6...c6 7.O-O Qa5
** Benoni/Benko: 2...c5 3.d5 (for 3.Nf3 see English, Anti-Benoni) then
*** [In-91] Modern Benoni: 3...e6 4.Nc3 exd5 5.cxd5 d6 6.Nf3 (or 4.Nf3 exd5 5.cxd5 d6 6.Nc3) 6...g6 7.e4 (or 6.e4 g6 7.Nf3 (alt. [In-93] Pawn Storm Variation: 7.f4 Bg7 bifurcates into Taimanov Variation 8.Bb5+ and Four Pawns Attack (A69) 8.Nf3 O-O 9.Be2 which is an independent position that can also arise from the KID Four Pawns Attack)) 7...Bg7
*** Benko Gambit: 3...b5 4.cxb5 (4.Nf3 is NIE due to 5.cxb5) 4...a6 then [In-95] Accepted: 5.bxa6 g6 6.Nc3 Bxa6 (or 5...Bxa6 6.Nc3 g6); [In-97] Declined: 5.b6
*** [In-99] Czech Benoni: 3...e5 4.Nc3 d6 5.e4 Be7
*** (for 3...g6 4.Nc3 see (eventually) King's Indian Defence after either 4...d6 5.e4 or 4...Bg7 5.e4)
* (2.Nf3 all transposes out:
** For 2...e6 see 1...d5 after any of 3.e3 d5, 3.e3 c5 4.c4 d5, 3.g3 d5 or 3.Bf4 d5, see 2.c4 after 3.c4, see Queen's Indian Defence after 3.e3 b6, or see Trompowsky after 3.Bg5.
** For 2...c5 see English Anti-Benoni after 3.c4 or Old Benoni after 3.d5.
** For 2...b6 see English Defence after 3.c4 e6 or see Queen's Indian Defence after 3.g3 Bb7 4.Bg2 e6 5.O-O Be7 6.O-O.
** For 2...d6 3.c4 see King's Indian Defence after 3...g6 or Old Indian after 3...Nbd7 4.Nc3 e5 5.e4.)
* (for 2.Nc3 d5 see Veresov's Opening)
* (for 2.g3 see Fianchetto King's Indian after 2...g6 or 1...d5 after 2...d5)

#### [Qp] Mutual Queen's Pawn: 1.d4 d5, then

* Queen's Gambit: 2.c4, then
** Slav Defence: 2...c6, then
*** 3.Nf3 Nf6 (for 3...e6 see 3.e3 after 4.e3, or 3.Nc3 after 4.Nc3) then
**** 4.Nc3, then
***** Semi-Slav: 4...e6, then
****** Botvinnik (Anti-Meran) Gambit: 5.Bg5 then (for 5...Nbd7 6.e3 Qa5 see Cambridge Springs Defence) [Qp-11] Botvinnik Gambit Accepted: 5...dxc4 6.e4 b5 7.e5 h6 8.Bh4 g5 bifurcates into Ekstrom Variation: 9.exf6; Lilienthal/Alatortsev Variations: 9.Nxg5, [Qp-13] Moscow Variation: 5...h6 6.Bxf6 Qxf6
****** 5.e3 Nbd7 (for 5...a6 see 4...a6), then
******* Meran Variation: 6.Bd3 dxc4 7.Bxc4 b5 8.Bd3 then [Qp-14] Blumenfeld Variation: 8...a6, [Qp-16] Wade Variation: 8...Bb7
******* 6.Qc2 Bd6 then [Qp-17] Chigorin Variation: 7.Bd3 (or 6.Bd3 Bd6 7.Qc2) 7...O-O 8.O-O dxc4 9.Bxc4, [Qp-19] 7.Be2
****** (for 5.cxd5 exd5 6.Bg5 see QGD, Exchange Variation)
***** Slav Accepted: 4...dxc4 5.a4 Bf5, then [Qp-21] Central Variation: 6.Ne5 Ndb7 7.Nxc4; [Qp-23] Dutch Variation: 6.e3 e6 7.Bxc4 Bb4 8.O-O O-O 9.Qe2 Nbd7 (or 8...Nbd7 9.Qe2 O-O)
***** Chameleon Slav: 4...a6, then [Qp-27] 5.c5, [Qp-29] 5.e3 b5 l/o ...dxc4
***** (for 4...Bf5 5.e3 - see 4.e3)
**** Quiet Variation: 4.e3, then
***** [Qp-31] Schallopp Defence: 4...Bf5 5.Nc3 e6 6.Nh4
***** (for 4...e6 see Semi-Slav after 5.Nc3 or (eventually) 5.Bd3 followed at some point by Nc3)
***** [Qp-33] Pin Defence: 4...Bg4
***** (4...a6 is NIE due to transposition to the Chameleon Slav with 5.Nc3)
**** (for 4.cxd5 cxd5 see Exchange Slav)
**** [Qp-34] 4.Qc2 l/o Nc3 r/o Qxc4, l/o ...e6 for Black which transposes to Catalan lines
**** [Qp-36] 4.Qb3
*** [Qp-37] 3.Nc3 then Triangle Slav: 3...e6 (for 3...Nf6 see 3.Nf3 after either 4.Nf3, 4.e3 a6 5.Nf3 or 4.e3 e6 Nf3) 4.Nf3 (for 4.e3 Nf6 5.Nf3 see Semi-Slav 5.e3) then Abrahams-Noteboom Variation: 4...dxc4 l/o ...Nf6 (for 4...Nf6 see Semi-Slav 3.Nf3 Nc6 4.Nc3 e6)
*** [Qp-39] Exchange Slav: 3.cxd5 cxd5 4.Nc3 Nf6 5.Bf4 Nc6 6.e3
*** (for 3.e3 see 3.Nf3 after 3...Nf6 4.Nf3 or 3.Nc3 after 3...Nf6 4.Nc3)
** Queen's Gambit Declined: 2...e6, then
*** 3.Nc3, then
**** 3...Nf6, then
***** [Qp-41] Exchange Variation: 4.cxd5 exd5 5.Bg5 Be7 6.e3 c6 (or 5...c6 6.e3 Be7)
***** 4.Nf3, then
****** [Qp-43] Ragozin Variation: 4...Bb4 5.cxd5 exd5 6.Bg5 (lines where White plays 5.Bg5 and avoids taking on d5 are NIE due to the additional transposition to the Vienna Variation)
****** Semi-Tarrasch Defence: 4...c5 then [Qp-45] Exchange Variation: 5.cxd5 Nxd5, [Qp-47] Symmetrical Variation: 5.e3 Nc6 6.a3
****** [Qp-49] Vienna Variation: 4...dxc4 5.e4 Bb4 6.Bg5
****** (for 4...c6 see Semi-Slav Defence)
****** (for 4...Be7 see Alatortsev Defence)
****** (for 4...Nbd7 see 4.Bg5 after 5.Bg5 or Exchange Variation after 5.cxd5 cxd5)
***** Pillsbury Attack: 4.Bg5, then
****** 4...Be7 5.Nf3 (5.e3 transposes back to 5.Nf3 after either 5...O-O 6.Nf3, 5...Nbd7 6.Nf3 or 5...h6 6.Bh4 O-O 7.Nf3), then
******* [Qp-51] Orthodox Variation: 5...Nbd7 6.e3 O-O (or 5...O-O 6.e3 Nbd7; for 6...h6 7.Bh4 see 5...h6) 7.Rc1
******* 5...h6 then [Qp-53] TMB System: 6.Bh4 O-O 7.e3 b6, [Qp-55] Anti-TMB System: 6.Bxf6 Bxf6
******* [Qp-57] 5...O-O 6.e3 h6 7.Bh4 (or 5...h6 6.Bh4 O-O 7.e3) then Lasker Variation: 7...Ne4 (for 7...b6 see TMB System)
****** [Qp-59] 4...Nbd7 5.Nf3 (for 5.e3 Be7 6.Nf3 see Orthodox Variation) then Cambridge Springs Defence: 5...c6 (for 5...Be7 see Classical Variation) 6.e3 Qa5
**** (for Triangle Defence: 3...c6 see Triangle Slav after 4.e3 or Semi-Slav after 4.Nf3 Nf6)
**** [Qp-61] Tarrasch Defence: 3...c5 4.cxd5 exd5 5.Nf3 Nc6 6.g3 Nf6 7.Bg2 Be7 8.O-O O-O 9.Bg5 cxd4 10.Nxd4
**** [Qp-69] Alatortsev Defence: 3...Be7 4.Nf3 Nf6 then Classical QGD: 5.Bf4 (for 5.Bg5 see Pillsbury Attack, Orthodox Variation) 5...O-O 6.e3 c5 7.dxc5 Bxc5
*** Catalan Opening: 3.Nf3 Nf6 (for 3...c5 see Semi-Tarrasch Defence after 4.e3 Nf6 5.Nc3, or see Tarrasch Defence after 4.cxd5 exd5 followed by Nc3 at some point; for 3...dxc4 see QGA; 3...c6 is NIE due to transpositions to Semi-Slav after 4.Qc2, 4.e3 Nf6 or 4.Nc3 Nf6) 4.g3 (for 4.Nc3 see 3.Nc3; for 4.Bg5 see 3.Nc3 after either 4...Be7 5.Nc3, 4...Nbd7 5.Nc3 or 4.Nbd7 5.e3 c6 6.Nc3; 4.e3 is NIE due to the following transpositions: for 4...c5 see Tarrasch Defence, for 4...dxc4 see QGA, for 4...c6 (or 4...Nbd7 5.Nc3 c6) see Semi-Slav, for 4...b6 5.Nc3 Bb7 see Queen's Indian) then
**** [Qp-71] Open Catalan: 4...dxc4 5.Bg2 l/o Be7 and Bb4+ for which see Closed Catalan and Improved Closed Catalan respectively (Closed Catalan includes some lines with the "open" 6...dxc4) includes various Queenside manoeuvres including 5...a6, 5...Nc6 and 5...c5
**** Closed Catalan: 4...Be7 5.Bg2 O-O 6.O-O then
***** Lines where Black avoids taking on c4: [Qp-74] 6...c6 7.Qc2 Nbd7 (or 6...Nbd7 7.Qc2 c6)
***** [Qp-76] 6...dxc4 7.Qc2 a6 bifurcates into 8.a4 and 8.Qxc4
**** [Qp-78] Improved Closed Catalan: 4...Bb4 5.Bd2 Be7 - can arise via Bogo-Indian but only as a minor sideline
** Queen's Gambit Accepted: 2...dxc4, then
*** [Qp-81] Centre Variation: 3.e4 l/o ...c6 and ...e6
*** [Qp-83] Classical Variation: 3.Nf3 Nf6 4.e3 (4.Nc3 is NIE due to the following transpositions: for 4...c6 see Slav Defence, for 4...e6 see 4.e3 after 5.e3 or see Ragozin after 5.e4 Bb4 6.Bg5) 4...e6 5.Bxc4 a6 6.O-O c5 (or 5...c5 6.O-O a6)
*** (for 3.e3 Nf6 see 3.Nf3 after either 4.Nf3 or 4.Bxc4 e6 5.Nf3)
** [Qp-87] Chigorin Defence: 2...Nc6 l/o ...c6 or...c5, also not including the 3.Nf3 e5 line that transposes to the Albin Counter-Gambit
** [Qp-89] Albin Counter-Gambit: 2...e5 3.dxe5 d4 4.Nf3 Nc6
* 2.Nf3, then
** [Qp-91] 2...Nf6 then Torre Attack: 3.Bg5 l/o c4 r/o c3 (for 3.c4 see Slav Defence after 3...c6, see QGD after 3...e6 or see QGA after 3...dxc4; for Colle System: 3.e3 e6 see 2...e6; for 3.Bf4 see London System; 3.g3 is NIE due to 3...e6 4.Bg2 Be7 5.O-O O-O 6.c4 transposing to Closed Catalan) bifurcates into ...e6 and ...Ne4, l/o ...g6 compared to Bg5 Ne4 lines of the King's Indian
** [Qp-93] 2...e6 3.e3 (3.c4 - see QGD; 3.g3 is NIE due to transpositions to the Closed Catalan) 3...Nf6 then Colle System: 4.Bd3 l/o c4 (for 4.c4 see QGD)
** (for 2...c6 3.c4 see Slav Defence)
** (Krause Defence: 2...c5 is NIE due to 3.c4 e6 transposing to QGD Tarrasch)
** (2...Nc6 is NIE due to 3.c4 transposing to QGD Chigorin Defence)
* [Qp-95] Mason's Opening: 2.Bf4 l/o c4 the main line is the London System, 2...Nf6 3.e3
* [Qp-97] Hodgson Attack: 2.Bg5 l/o 2...Nf6 for which see Trompowsky Opening, bifurcates into 2...h6 and 2...c6
* [Qp-99] Veresov's Opening: 2.Nc3 l/o c4, then 2...Nf6 3.Bg5 Nbd7

#### [Qs] 1.d4 - everything else

* 1.d4 e6 2.c4 (for 2.Nf3 see Dutch Defence after 2...f5, see 1...Nf6 after 2...Nf6 or see 1...d5 after 2...d5; for 2.e4 see French Defence), then
** [Qs-11] English Defence: 2...b6 many many independent lines result from this, none of them significant enough. Black may avoid transposing out by avoiding ...Nf6, thus reserving the option of ...f5. White may avoid transposing out by avoiding e3, thus reserving the option of e4.
** (Keres (Kangaroo) Defence 2...Bb4+ is NIE due to most lines transposing to Nimzo- or Bogo-Indians; [Qs-2] is reserved for it anyway)
** (for 2...Nf6 see 1...Nf6)
** (for 2...d5 see 1...d5)
** (for 2...f5 see Dutch Defence)
* Dutch Defence: 1.d4 f5 then
** 2.g3 Nf6 3.Bg2 then
*** Leningrad Dutch: 3...g6 4.Nf3 Bg7 5.O-O O-O 6.c4 d6 7.Nc3 then [Qs-31] Main Line: 7...Qe8, [Qs-35] Matulovic Variation: 7...Nc6, [Qs-39] Warsaw Variation: 7...c6
*** non-Leningrad Dutches: 3...e6 4.c4 then [Qs-41] Stonewall Dutch: 4...d5 5.Nf3 c6 (White and/or Black can reverse the order of their last 2 moves) 6.O-O Bd6, [Qs-49] Classical Dutch: 4...Be7 5.Nf3 (or 4.Nf3 Be7 5.c4) 5...O-O 6.O-O
** [Qs-51] Anti-Dutch: 2.Bg5
** [Qs-59] Raphael Variation: 2.Nc3 l/o c4
** (2.c4 is NIE due to the following: for 2...e6 3.g3 Nf6 4.Bg2 see non-Leningrad Dutches; after 2...Nf6 any of the three moves 3.g3, 3.Nf3 and 3.Nc3 give Black the two options: for 3...e6 see non-Leningrad Dutches, for 3...g6 see Leningrad Dutch)
** (for 2.Nf3 see 2.g3 after 2...Nf6 3.g3, see 2.c4 after either 2...Nf6 3.c4 or 2...e6 3.c4, otherwise for 2...e6 see Stonewall Dutch after 3.g3 Nf6 4.Bg2 d5 5.c4 c6 6.O-O Bd6; for 2...g6 see Leningrad Dutch)
* Old Indian: 1.d4 d6, then the independent line is the [Qs-61] Wade Defence: 2.Nf3 Bg4 (everything else transposes out as follows:
** Neo-Old Indian: 2.Nf3 then 2...g6 3.c4 Bg7 4.Nc3 is NIE due to 4...Nf6 transposing to King's Indian Defence and 4...Nd7 5.e4 transposing to Modern Averbakh; for 2...Nf6 see 2.c4 after 3.c4 or see Fianchetto King's Indian after 3.g3 g6 4.Bg2 Bg7 (or 2...g6 3.g3 Bg7 4.Bg2 Nf6)
** for 2.c4 see 1...Nf6 2.c4, Old Indian after 2...Nf6 or see Modern, Averbakh after 2...g6 3.Nc3 Bg7 4.e4; Pillsbury Defence 2...e5 is NIE due to 3.Nc3 transposing to King's English
** for 2.e4 see Pirc Defence)
* [Qs-71] Old Benoni: 1.d4 c5 2.d5 (for 2.e4 see Sicilian, Smith-Morra Gambit) then Old Czech Benoni: 2...e5 (for 2...Nf6 3.c4 - see Modern Benoni) 3.e4 d6 where White avoids the Modern Czech Benoni by avoiding c4 and/or Black avoids it by avoiding ...Nf6
* (Robatsch Defence: 1.d4 g6 all transposes out as follows:
** 2.c4 Bg7 (for 2...Nf6 see 1...Nf6) see Modern, Averbakh after either 3.Nc3 d6 4.e4, 3.e4 d6 4.Nc3 or 3.Nf3 d6 4.Nc3 Nf6 (or 3...Nf6 4.Nc3 d6); see 1...Nf6 after either 3.Nc3 Nf6 or 3.Nf3 Nf6, see Modern Benoni after 3.Nc3 c5
** 2.g3 Bg7 3.Bg2 most commonly transposes out to Fianchetto King's Indian; the independent line 3...d6 4.e4 is NSE (there isn't a Fianchetto Modern Defence to transpose to)
** 2.Nf3 Bg7 (for 2...Nf6 see 1...Nf6; for 2...d6 see either Modern Defence 2...g6 after 3.e4, King's Indian Defence after 3.c4 or Fianchetto King's Indian after 3.g3; for 2...f5 see Leningrad Dutch) then 3.c4 (for 3.e4 see Modern Defence, Averbakh after 3...d6 4.Nc3, Modern Benoni after 3...c5 4.d5 or Sicilian Hyper-Accelerated Dragon after 3...c5 4.Nf3; for 3.g3 see Fianchetto King's Indian) 3...d6 (for 3...Nf6 see 1...Nf6; for 3...f5 see Leningrad Dutch) 4.Nc3 Nf6 see King's Indian Defence
** 2.e4 - see Modern Defence)
* (for 1.d4 c6 see Caro-Kann Defence after 2.e4, Slav Defence after 2.c4 d5 or 1...Nf6 after 2.c4 Nf6)
* (for 1.d4 b6 see Owen's Defence after 2.e4)
* (for 1.d4 e5 see Centre Game after 2.e4 (Englund Gambit Accepted is NSE))
* (1.d4 Nc6 Bogoljubow-Miles Defence is NIE due to transposition to Chigorin Defence with 2.c4 d5; [Qs-8] reserved for it)

### Réti Opening: 1.Nf3

White has 80,000 ways of transposing to a 1.d4 opening after 1.Nf3. A point at which White has the additional option of playing d4 is indicated by *.
1.Nf3 d5 * then
* Main Line: 2.c4 then [Fl-11] Reverse Benoni: 2...d4 (for 2...e6 * 3.g3 Nf6 or 2...c6 * 3.e3 Nf6 see 1...Nf6)
* King's Indian Attack, Yugoslav Defence: 2.g3 c6 (for 2...Nf6 see 1...Nf6) 3.Bg2 Bg4 (or 2...Bg4 3.Bg2 c6) - see King's Indian Attack Island
* [Fl-19] Nimzowitsch-Larsen Attack: 2.b3
1.Nf3 Nf6 * then
* 2.c4 then
** [Fl-21] 2...e6 * 3.Nc3 (for 3.g3 see 2.g3) then Nimzo-English: 3...Bb4 l/o d4 (for 3...d5 4.d4 see 1.d4)
** [Fl-25] 2...g6 * 3.Nc3 (for 3.g3 see 2.g3) 3...d5 * (for 3...Bg7 * see 2.g3 after 4.g3 or King's Indian Defence after 4.e4 d6 5.d4) then Grünfeld Réti: 4.cxd5 Nxd5 - lines where White leaves out d4 (5.e4 Nxc3 is mostly met with dxc3 avoiding the transposition to the Grünfeld)
** (for 2...c5 - see Symmetrical English)
** (for 2...b6 * 3.g3 see 2.g3)
** (for 2...d6 3.d4 - see 1.d4)
** (for 2...c6 * 3.Nc3 d5 * 4.e3 e6 5.d4 see 1.d4 Semi-Slav)
* [Fl-29] Nimzowitsch Attack: 2.b3 g6 3.Bb2 Bg7 4.g3 O-O 5.Bg2 where Black leaves out ...d5 transposing to the Nimzowitsch-Larsen Attack
* (King's Indian Attack Réti: 2.g3 all transposes out as follows:
** 2...b6 3.Bg2 (3.c4 transposes to this after either 3...Bb7 4.Bg2 or 3...e6 4.Bg2; Black can also transpose out to the English with ...c5 at move 3, 4, 5 or 6) 3...Bb7 4.c4 (for 4.O-O see Hedgehog English) 4...e6 * 5.O-O Be7 * 6.Nc3 then for Anglo-Queen's Indian: 6...O-O 7.d4 see 1.d4, Queen's Indian Defence (7.Re1 is NSE)
** for 2...d5 see 1...d5
** 2...g6 * 3.Bg2 (3.c4 Bg7 * 4.Bg2 see 3.Bg2 Anglo-Indian) 3...Bg7 * 4.c4 O-O 5.O-O (or 4.O-O O-O * 5.c4) 5...d6 * 6.Nc3 e5 see Bremen English)
[Fl-31] 1.Nf3 c5 then Barcza System: 2.g3 (for 2.e4 see Sicilian Defence; for 2.c4 see Symmetrical English) 2...Nc6 3.Bg2 l/o c4 or e4
(for 1.Nf3 g6 * 2.c4 Bg7 (for 2...c5 see Symmetrical English; for 2...Nf6 see 1...Nf6) 3.d4 (or 3.Nc3 d6 4.d4) see 1.d4)
(for 1.Nf3 f5 * 2.g3 Nf6 * see Anglo-Dutch after 3.c4 or Leningrad Dutch after 3.Bg2 g6)
(for 1.Nf3 d6 2.d4 see 1.d4)
(for 1.Nf3 e6 * 2.c4 see 1...Nf6 after 2...Nf6 or 1...d5 after 1...d5)

### English Opening: 1.c4

White has 80,000 ways of transposing to a 1.d4 opening after 1.c4. A point at which White has the additional option of playing d4 is indicated by *
White also has 12,000 ways of transposing to a 1.Nf3 opening after 1.c4. A point at which White has the additional option of playing Nf3 is indicated by †
[Fl-41] Anglo-Indian: 1.c4 Nf6 *† 2.Nc3 (for 2.g3 see 1...e5 after 2...e5 or 1...c5 after 2...g6 *† 3.Bg2 Bg7 *† 4.Nc3 O-O *† 5.e4 d6 6.Nge2 c5; 2...e6 *† 3.Bg2 d5 *† is NIE) 2...e6 *† (for 2...g6 *† see 2.g3 after 3.g3 or 1.d4 after 3.e4 d6 4.d4; for 2...e5 see 1...e5; for 2...c5 see 1...c5; Grünfeld English 2...d5 3.cxd5 Nxd5 4.g3 is NIE due to transpositions to the Reversed Sicilian with ...e5 or the Neo-Grünfeld with d4) then Mikenas Attack: 3.e4 l/o d4
[Fl-45] Anglo-Slav: 1.c4 c6 * 2.Nf3 (for 2.e4 see Caro-Kann, English Variation) 2...d5 * 3.e3 Nf6 4.Nc3 l/o d4 for which see Semi-Slav
[Fl-49] Anglo-Dutch: 1.c4 f5 - lines where White avoids transposing to a regular Dutch with d4
(1.c4 b6 is NIE due to transpositions to the English Defence with d4)
Reversed Sicilian 1.c4 e5 2.Nc3 (2.g3 transposes to this after 2...Nf6 3.Bg2 d5 4.cxd5 Nxd5 5.Nc3, 2...Nf6 3.Nc3, 2...Nc6 3.Nc3, 2...Nc6 3.Bg2 Nf6 4.Nc3, 2...Nc6 3.Bg2 g6 4.Nc3 or 2...d6 3.Nc3), then
* [Fl-51] 2...Nc6 then Closed English: 3.g3 (for 3.Nf3 Nf6 see 2...Nf6) 3...g6 4.Bg2 Bg7
* [Fl-53] King's English: 2...d6 l/o ...Nf6 r/o ...f5
* 2...Nf6 then Bremen System: 3.g3 (alt. [Fl-55] English Four Knights: 3.Nf3 Nc6 4.g3 - lines where Black doesn't transpose to the Reversed Dragon with ...d5, including ...Bb4, ...Bc5 and ...Nd4), then
** [Fl-57] Reversed Dragon: 3...d5 4.cxd5 Nxd5 5.Bg2 Nb6 6.Nf3 Nc6 7.O-O Be7
** [Fl-59] Smyslov System: 3...Bb4 l/o...Nc6, for which see English Four Knights
* (Kramnik-Shirov Counterattack: 2...Bb4 is NIE due to transpositions to Smyslov System and Closed English)
(for Anglo-French Defence: 1.c4 e6 *† see 1...Nf6 after 2.Nc3 Nf6, 2.g3 Nf6, 2.g3 d5 3.Nf3 Nf6 or 2.g3 d5 3.Bg2 Nf6 or see QGD after 2.Nc3 d5 3.d4)
Symmetrical English: 1.c4 c5, then
* [Fl-61] Ultra-Symmetrical English: 2.g3 g6 3.Bg2 Bg7 4.Nc3 Nc6 5.Nf3
* (for 2.Nc3 see Ultra-Symmetrical English after 2...g6 or 2...Nc6 3.g3 g6, or see 2.Nf3 after 2...Nc6 3.Nf3 or 2...Nf6 3.Nf3)
* 2.Nf3 Nf6 (for 2...Nc6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e6 see 2...Nf6, Symmetrical Two Knights; for 2...Nc6 3.Nc3 g6, 2...g6 3.g3 or 2...g6 3.Nc3 see Ultra-Symmetrical English; for 2...g6 3.d4 Bg7 4.e4 cxd4 5.Nxd4 Nc6, 2...g6 3.d4 cxd4 4.Nxd4 Bg7 5.e4 Nc6 or 2...Nc6 3.d4 cxd4 4.Nxd4 g6 5.e4 see Sicilian Maroczy Bind) then
** [Fl-63] 3.Nc3 then Modern Variation: 3...d5 (for 3...e6 see Hedgehog Defence after 4.g3 b6, Anti-Benoni after 4.d4 or QGD Semi-Tarrasch after 4.e3 d5 5.d4; for 3...Nc6 see 2...Nc6) 4.cxd5 Nxd5 bifurcates into 5.g3 and 5.d4 l/o e4 compared to Exchange Grünfeld
** 3.d4, then
*** 3...cxd4 4.Nxd4, then
**** [Fl-64] Anti-Benoni: 4...e5
**** (4...Nc6 5.Nc3 is NIE due to transposing to Symmetrical Two Knights with 5...e6 and Sicilian Maroczy Bind with 5...g6 6.e4)
**** (4...Nc6 5.g3 is NIE due to transpositions to Anglo-Catalan)
**** (4...e6 5.g3 see Anglo-Catalan)
**** (4...e6 5.Nc3 l/o g3 see Symmetrical Two Knights)
*** 3...e6, then
**** [Fl-65] Anglo-Catalan: 4.g3 cxd4 5.Nxd4 (or 3...cxd4 4.Nxd4 e6 5.g3) after which 5...d5 is the most common move, with the resulting positions classified as Symmetrical English, Catalan Variation rather than Catalan, ...c5 Variation
**** [Fl-66] Symmetrical Two Knights: 4.Nc3 cxd4 5.Nxd4 where White avoids g3 transposing to the Anglo-Catalan and Black avoids the combination of ...Be7 and ...d5 transposing to the QGD Tarrasch
**** (for 4.e3 d5 see QGD Tarrasch)
**** (for 4.d5 see Modern Benoni)
*** (for 3...g6 see 2.Nf3 g6)
** 3.g3 b6 4.Bg2 Bb7 5.O-O then [Fl-67] Hedgehog Defence: 5...e6 6.Nc3 Be7 7.d4 cxd4 8.Qxd4, [Fl-69] Double Fianchetto Defence: 5...g6
(Great Snake: 1.c4 g6 *† transposes out as follows:
* 2.g3 Bg7 (for 2...Nf6 see Anglo-Indian) 3.Bg2 (for 3.Nc3 see 2.Nc3) 3...Nf6 *† (for 3...c5 see 1...c5) 4.Nc3 - see 3.Nc3
* 2.Nc3 Bg7 * (for 2...Nf6 see Anglo-Indian; for 2...c5 see 1...c5) 3.g3 see 2...Nf6 after 3...Nf6 or see 1...e5 after 3...e5
* 2.e4 Bg7 3.d4 - see 1.d4)

### Benko Opening: 1.g3

NIE due to transpositions to Réti King's Indian Attack after 1...e5 2.Bg2 d5 and 1...Nf6 2.Bg2, English after 1...e5 2.c4 and 1...g6 2.Bg2 Bg7 3.c4, and 1.Nf3 after 1...d5 2.Nf3 and 1...d5 2.Bg2 Nf6 3.Nf3. Use Fl-3

### Bird's Opening: 1.f4

* [Fl-71] 1...d5 2.Nf3

### Larsen's Opening: 1.b3

* [Fl-81] Classical Variation: 1...d5 2.Bb2 where White avoids playing Nf3 transposing to the Réti
* [Fl-89] Modern Variation: 1...e5 2.Bb2 Nc6 3.e3

### Dunst Opening: 1.Nc3

NIE due to transpositions to almost every other opening. Independent lines 1...d5 2.e4 d4 and 1...d5 2.e4 dxe4 are NSE. Use Fl-91

### [Fl-99] Sokolsky Opening: 1.b4
## Very abridged list (100,000 games per 50,000 1.e4 games)

| | a | b | c | d | e | f | g | h | |
| 8 | | | | | | | | | 8 |
| 7 | | | | | | | | | 7 |
| 6 | | | | | | | | | 6 |
| 5 | | | | | | | | | 5 |
| 4 | | | | | | | | | 4 |
| 3 | | | | | | | | | 3 |
| 2 | | | | | | | | | 2 |
| 1 | | | | | | | | | 1 |
| | a | b | c | d | e | f | g | h | |