context: 1. e2e4  1... c7c5  2. g1f3  2... d7d6  3. f1b5 The Moscow line is very popular nowadays. 3... b8d7 This move leads to a complex battle. 4. e1g1  4... a7a6  5. b5d3 The main variation. 5... g8f6  6. f1e1 