Sicilian Defense: Old SicilianBETA

2. ...Nc6 continues development and covers the d4 and e5 squares while still keeping retaining the option to push either d5 or e5 in one move.

Within the Open Sicilians after 3. d4 it is most frequently used as the move order to reach a Sveshnikov setup after a subsequent 3. ...cxd 4. Nxd Nf6 5. Nc3 e5 - where the central pressure and threat of Bb4 force White into the complications that arise from 6. Ndb5. Another very important option is the Accelerated Dragon after 3. d4 cxd 4. Nxd g6 - where the purpose of Nc6 was to rule out a White Qxd4.

While these variations give 2. ...Nc6 individual significance, there are also transpositions to other move orders. The Taimanov for instance can be reached after 2. ...Nc6 3. d4 cxd 4. Nxd e6, or with 2. ...e6 4. ...Nc6. Most transpositions to other variations are less popular in current theory because 2. ...Nc6 is considered a committal move as it allows White to play the Rossolimo with 3. Bb5.

Both the Open Sicilians and the Rossolimo are near guaranteed to lead to sharp asymmetrical positions, many of which have spawned long theoretical lines. The White pressure rarely translates to quick mating attacks, more often it is based on a positional weakness (such as the d5 square in the Sveshnikov or a doubled c pawn in the Rossolimo) that stymies the Black play deep into the middlegame.

Further options for White include 3. c3 3. Nc3, or 3. g3 to transpose to Alapin or Closed Siclians but none of these move orders has individual significance as an early Nc6 is a thematic move for Black in these systems anyway.