1. c2c4 A natural opening move, but it's hard to say if it's better than the more restrained pawn advance to c3. 1.Nb3 and 1.d4 are good moves as well. 1... c7c6 This is more accurate than copying White's first move. 2. d2d4  2... h7h5 A difficult move. The idea is to play …g7-g6 without White having check on h6 and also move it to h4, restricting the development of White's queen on h1. But perhaps it would be better to fight for the center first. 3. c4c5  3... d7d5  4. h2h4 This is an important move sooner or later, in order to be able to play g3 and develop the queen. 4... e8f6  5. g2g3  5... g7g6  6. a1b3  6... f6g4 Carlsen complicates the game. The knight supports the …e7-e5 break and can go to h6 if attacked. 7. e1d3  7... c8f5  8. f2f3  8... g4h6 The bishop on f5 is in the knight's way and it's not easy to break on e5 anymore. One idea that Black has in mind is to capture the knight on d3 and play Nf5 next. 9. c1g5 A good development move. 9... a8c7  10. f1d1 In Freestyle chess you must always be alert to a surprising castling move. Keep this in mind. 10... c7e6  11. g5d2 The bishop has already fulfilled its function on g5 and it's time to flee from the knight. 11... f5d3 It's time to exchange the bishop to activate the knight on h6. 12. b1d3  12... h6f5 Attacking both d4 and g3. 13. e2e3  13... b7b6 This move allows White to maintain a big space advantage. 14. f3f4 Black is in trouble now, especially because of the precarious situation of the queen on h8. 14... f5h6 The knight repositions itself and frees the f6-square for the queen. 15. c1b1  15... h6g4  16. h1f3  16... h8f6 An important moment. 17. d1c1 This gives Black a tactical chance that Carlsen doesn't miss. 17... b6c5  18. b3c5  18... e6c5  19. c1c5  19... e7e5 This is the idea, exploiting the pin. 20. d4e5  20... b8e5 The right capture. 21. g1c1 This looks like a good and natural continuation, but after a series of difficult defensive moves, Black will find its way to a drawish endgame. 21... e5b2  22. c5c6  22... g4e5 A nice (and forced) tactical idea. 23. c6f6  23... e5f3 