comment: What can I say about this play $2 It seems absurd, but it's a fantastic and interesting idea, at the very least useful for a rapid game. The white knight is lost against other moves as well, but White usually try more conventional lines in the search for compensation.
context: 1. c2c4  1... g8f6  2. b1c3  2... e7e5  3. g1f3  3... b8c6  4. g2g3  4... f8b4  5. f1g2  5... e8g8  6. c3d5  6... e5e4 This is considered the best reply according to theory, although other moves are possible. 7. f3h4  7... d7d6  8. e1g1  8... g7g5 Black bravely goes after the knight. There is a price to pay: the king is weakened. 9. d2d4  9... h7h6 This position has already been played in more than 80 games, and now comes something new from Caruana's opening lab that borders on the unbelievable.