Up to here, everything has been pretty well-known theory. Now, while Ian's next move is very natural, I think it is not best.
1. c2c4  1... e7e5  2. g2g3  2... c7c6  3. g1f3  3... e5e4  4. f3d4  4... d7d5  5. c4d5  5... d8d5  6. d4c2  6... g8f6  7. b1c3  7... d5e5  8. f1g2  8... b8a6  9. e1g1  9... f8e7 