1. e2e4  1... e7e5  2. g1f3  2... g8f6 Here we have the good old Petroff again. Is this defense taking the Berlin's place as Black's bulletproof option against 1. e4 $2 3. d2d4  3... f6e4  4. d4e5  4... d7d5  5. b1d2  5... e4d2  6. c1d2  6... f8e7  7. f1d3 