Another rare move. 4.e3, 4.Nf3 or 4.Nc3 would leave possible transpositions in the air.
1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. c1f4 When we start playing chess, we are taught that we should normally develop knights before bishops. It's no surprise, then, that this move isn't popular. Normally it would be possible to transpose to well-known lines, but in a curious way the game quickly takes unique contours. 3... d7d5 