1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1c4  3... g8f6  4. d2d3  4... d7d5 [%c_effect d5;square;d5;type;Interesting;persistent;true] The belief in the old days was that this very fast advance is bad for Black, but as I've written a few times, the computer shows that everything is more or less playable. 5. e4d5 