d2-d4:Queen's pawn opening
  d7-d5:Queen's pawn/stonewall attack
    c2-c4
      e7-e6:Queen's gambit declined
        b1-c3
          g8-f6
            c1-g5
              b8-d7
          f8-b4
        e2-e3:Queen's gambit/Cambridge Springs
          c7-c6
            g1-f3
              d8-a5
                b1-d2
        g1-f3
          g8-f6
            e2-e3
              c7-c6
                b1-d2:Queen's gambit declined/Slav
      g7-g6
        g2-g3
      d5xc4:Queen's gambit accepted
        e2-e4
          c7-c5
            d4-d5
              g8-f6 
                b1-c3 
                  b7-b5:Queen's gambit accepted/Linares
          f7-f5:Queen's gambit accepted/Schwartz defence
    c1-f4:Queen's pawn/Mason variation
    c1-g5:Levitsky attack (Queen's bishop attack)
      h7-h6
        g5-h4
          c7-c6
            g1-f3
    b1-c3:Queen's pawn/Chigorin variation
    g1-f3:Queen's pawn game
  g8-f6
    c2-c4
      g7-g6:King's Indian defence
        b1-c3
          f8-g7
            e2-e4
              d7-d6
                g1-f3
                  O-O
                    f1-e2
                      e7-e5
                        O-O
                          b8-a6
                          b8-c6
                            d4-d5
      e7-e5:Budapest defence declined
        d4xe5
          f6-g4
          f6-e4
      d7-d6:Old Indian defence
        b1-c3
        g1-f3
        g2-g3
      c7-c5
        d4-d5:Benoni defence
          d7-d6:Benoni defence/Hromodka system
          e7-e5:Czech Benoni defence
            b1-c3
              d7-d6
          g7-g6
            b1-c3
          e7-e6
            b1-c3
          b7-b5:Benko gambit
            c4xb5:Benko gambit half accepted
              a7-a6
                b5xa6:Benko gambit accepted
                  c8xa6
                    b1-c3
                      d7-d6
        e2-e3
      e7-e6
        b1-c3
    g1-f3
      c7-c5
      d7-d6
      e7-e6
        e2-e3
        g2-g3
        c1-f4
        c1-g5:Queen's pawn/Torre attack
      b7-b6:Queen's Indian defence
        e2-e3
        g2-g3
        c1-f4
      g7-g6:King's Indian/East Indian defence
        c1-f4:King's Indian/London system
        c1-g5:King's Indian/Torre attack
          f8-g7
        g2-g3:King's Indian/fianchetto
    c1-g5:Trompovsky attack
      c7-c5
      e7-e6
        e2-e4
      g7-g6
        e2-e4
        g5xf6
          e7xf6
    e2-e3:Stonewall attack system
      c7-c5
      d7-d5
      e7-e6
      g7-g6
    f2-f3:Paleface attack
    f2-f4:Canard opening?
    g2-g3
    c2-c3

  e7-e6
    c2-c4
      c7-c5
        d4-d5
          e6xd5
            c4xd5
      b7-b6:Keres defence
      f8-b4:Queen's pawn/Franco-Indian defence
  b7-b5:Polish defence
  b7-b6:Queen's pawn/English defence
  g7-g6:Modern defence
    c2-c4
      f8-g7
        e2-e4
          d7-d6
          c7-c5
        b1-c3
        g1-f3
          d7-d6
    g1-f3
      f8-g7
      g8-f6
    e2-e4
      f8-g7
        c2-c4
          d7-d6
  b8-c6:Queen's pawn/Lundin defence?
    e2-e4:Queen's pawn-King's pawn game
      e7-e5
        d4-d5
  d7-d6:Queen's pawn game
    c2-c4:Old Indian defence
      g7-g6
        b1-c3:Modern defence
          f8-g7
            e2-e4:Modern defence/Averbakh system
            g1-f3
              c8-g4
      e7-e5:Old Indian defence?
        d4xe5:Old Indian/exchange
        g1-f3
        e2-e4
    g1-f3
      g7-g6
      c8-g4:Old Indian/Tartakower
  c7-c5:Old Benoni defence
    d4-d5
      d7-d6
      e7-e6:Old Benoni/Franco-Benoni defence
      f7-f5:Old Benoni/Mujannah formation
      g8-f6
        b1-c3
          d8-a5:Woozle defence
        g1-f3
        c2-c4
      e7-e5:Old Benoni defence
    d4xc5:Rodney Dangerfield defence
      e7-e6
        b1-c3
          f8xc5
            c3-e4
              g8-f6
                e4xc5
                  d8-a5  
    g1-f3:Benoni-Torre
      g8-f6
        d4-d5
          b7-b5
  f7-f5:Dutch
  e7-e5:Queen's pawn/Charlick gambit?
  c7-c6
    e2-e4
      d7-d5
        b1-c3
          d5xe4:Caro-Kann defence

e2-e4:King's pawn opening
  c7-c5:Sicilian defence
    b1-c3:Sicilian/closed
      b8-c6
        g2-g3
        f2-f4
        f1-b5
          g7-g6:Sicilian/Nimzovich-Rossolimo attack
        g1-e2:Sicilian/chameleon variation
        g1-f3
      d7-d6
        g1-e2
      e7-e6
    g1-f3:Sicilian defence/King's knight variation
      b8-c6:Sicilian defence
        c2-c3:Sicilian/Alapin's variation
          g8-f6
            e4-e5
              f6-d5
        d2-d4
          c5xd4
            f3xd4
              e7-e5
              g8-f6
      d7-d6:Sicilian/Kopec variation
      e7-e6
        b1-c3
        c2-c3:Sicilian/Alapin's variation
      g7-g6:Sicilian/Hungarian variation
      b7-b6:Sicilian/Katalimov variation
      d8-c7:Sicilian/Quinteros variation
      a7-a6:Sicilian/O'Kelly variation
      g8-f6:Sicilian/Nimzovich-Rubinstein variation
    f1-c4:Sicilian/Philidor
      e7-e6
      b8-c6
    g1-e2:Sicilian/Keres variation?
    c2-c3:Sicilian/Alapin's variation
      g8-f6
      g7-g6
      b7-b6
    b2-b3
    b2-b4:Sicilian/wing gambit?
      c5xb4
        a2-a3
          d7-d5
            e4xd5
              d8xd5
                c1-b2
    c2-c4
    d2-d3
    g2-g3:Sicilian/Steinitz variation
    d2-d4:Sicilian/Smith-Morra gambit?
      c5xd4
        g1-f3
        c2-c3
    f2-f4:Sicilian/Grand Prix attack
    f1-e2:Slow Sicilian
  e7-e5:King's pawn game
    g1-f3:King's knight opening
      b8-c6
        f1-c4
          f8-c5
        f1-b5:Spanish opening
          a7-a6
            b5-a4
        d2-d4:Scottish game
          e5xd4
            f3xd4
              g8-f6
              f8-c5
      d7-d6:Philidor's defence
        d2-d4
        f1-c4
      d7-d5:Queen's pawn counter-gambit
      f7-f6:Damiano's defence
      d8-e7:Brazilian (Gunderam) defence?
      d8-f6:Greco defence?
      g8-f6:Petrov's defence
      f7-f5:Latvian counter-gambit?
    f1-c4:Bishop's opening
    d2-d4
      e5xd4:Centre game
        c2-c3:Danish gambit
        d1xd4
    b1-c3:Vienna game
    f2-f4:King's gambit
      e5xf4:King's gambit accepted
        g1-f3
          g7-g5
    c2-c3:King's pawn/Lopez opening
    d2-d3:King's pawn/Indian opening
    g1-e2:Alapin's opening
    a2-a3:Mengarini's opening
    d1-f3:Napoleon's opening?
    f2-f3:King's head opening
    d1-h5:Patzer opening
  g7-g6:Robatsch opening
    d2-d4
      f8-g7:Robatsch defence
        b1-c3
          d7-d6
        g1-f3
      g8-f6:Norwegian defence
        e4-e5
          f6-h5
            g2-g4
              h5-g7
      c7-c6
        g1-f3
      d7-d6
    b1-c3:Robatsch opening?
      f8-g7
  d7-d6:Pirc
    d2-d4
      g7-g6:Pirc-Robatsch
      g8-f6:Pirc defence
        b1-c3
          g7-g6
          c7-c6
          e7-e5
        f2-f3
        f1-d3
      c7-c6

  e7-e6:French defence
    d2-d4
    e4-e5:French/Steinitz attack
    d2-d3:French/King's Indian attack
    b2-b3:Reti (Spielmann) variation
    c2-c4:French/Steiner variation
    f2-f4:French/Labourdonnais variation
    b1-c3
    g1-f3
    d1-e2:French/Chigorin variation
    c2-c4

  b7-b6:Owen defence?
    d2-d4
      e7-e6
      c8-a6:Guatemala defence?

  a7-a6:St.George defence?
  h7-h6:Carr's defence?
  b8-c6:King's pawn/Nimzovich defence
    d2-d4
      d7-d5
      e7-e5
    g1-f3
  d7-d5:Scandinavian defence?
    e4xd5
      g8-f6
        c2-c4
        d2-d4
        f1-b5
      d8xd5
        b1-c3
          d5-a5
          d5-d6
  g8-f6:Alekhine's defence?
    d2-d3:Alekhine's defence/Maroczy variation?
    e4-e5
      f6-d5
        d2-d4
  c7-c6:Caro-Kann defence
    b1-c3
      d7-d5
        g1-f3
    d2-d4
      d7-d5
        b1-c3
          d5xe4
      g8-f6:Caro-Masi defence
      g7-g6
    d2-d3:Caro-Kann/closed
    c2-c4:Caro-Kann/anti-Caro-Kann defence
      e7-e5
      d7-d5:Caro-Kann/anti-anti-Caro-Kann defence
  g7-g5:Borg defence?
    d2-d4
      h7-h6

g1-f3:Reti opening?
  d7-d5
    g2-g3:Reti King's Indian attack
    b2-b3
    c2-c4
      d5xc4:Reti accepted
  d7-d6
  g8-f6
  g7-g6
    d2-d4 
      f8-g7
  c7-c5:Reti plus English
    g2-g3
      g7-g6
      b8-c6
      e7-e6:Reti opening
      f7-f5:Reti Dutch
      g7-g6:Reti King's Indian
      b8-c6:Reti opening

c2-c4:English
  b7-b6
  f7-f5:English/Anglo-Dutch defence
  g7-g6
  c7-c6:Caro-Kann defensive system
    g1-f3
      d7-d5
        e2-e3
        g2-g3
        d1-c2
  g8-f6:English, New York defensive system
    g1-f3:English opening
    b1-c3:English Anglo-Gruenfeld
      d7-d5
        c4xd5
          f6xd5
            g2-g3
            g1-f3
      c7-c6
      g7-g6
      e7-e6
        g1-f3
        e2-e4
  e7-e6:English opening
  g8-f6:English, Anglo-Indian defence
  e7-e5:English opening
    g2-g3
    g1-f3
    g2-g3
    b1-c3
      g8-f6
      b8-c6:English, Sicilian reversed
        g1-f3:English/3 knights system
      d7-d6
      f7-f5
  c7-c5:English symmetrical
    g1-f3
    g2-g3
    b1-c3
g2-g3:Benko's opening?
  d7-d5
    f1-g2
  e7-e5
    f1-g2
b2-b3:Nimzovich-Larsen attack?
  c7-c5:Nimzovich-Larsen/English
  d7-d5:Nimzovich-Larsen/classical
  e7-e5:Nimzovich-Larsen/modern
  f7-f5:Nimzovich-Larsen/Dutch
  g8-f6:Nimzovich-Larsen/Indian
d2-d3:Mieses opening?
e2-e3:Van't Kruijs opening?
  e7-e5:Amsterdam attack
g2-g4:Grob's attack?
b1-c3:Dunst opening?
c2-c3:Saragossa opening?
h2-h3:Clemenz opening?
a2-a3:Anderssen's opening?
f2-f3:Gedult's opening?
h2-h4:Kadas opening?
b2-b4:Polish opening?
b1-a3:Durkin's attack?
g1-h3:Amar opening?
f2-f4:Bird's opening?
  d7-d5
    d2-d4
a2-a4:Ware opening?



 


