The main move.
1. c2c4  1... g8f6  2. g1f3  2... e7e6  3. g2g3  3... d7d5  4. f1g2  4... f8e7  5. e1g1  5... e8g8  6. d2d3 I didn't know this move, which is humble in appearance, but this position has been tried many times by strong players, although overwhelmingly in rapid or blitz games.