1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1b5  3... a7a6  4. b5a4  4... g8f6  5. e1g1  5... f8e7  6. d2d3  6... b7b5  7. a4b3  7... d7d6 Together with 8.a4 and 8.c3, this is one the main lines of this Ruy Lopez system. 8. a2a3  8... c6a5 A known move, but much rarer than the most natural castling. 9. b3a2  9... c7c5  10. b1c3 