user20776: In 2018, Magnus Carlsen played a rapid game on chess.com against Grandmaster Aleksey Dreev in which his opening move was 1. Nh3.
[Title "Magnus Carlsen-Alexey Dreev, Pro Chess League, chess.com INT, 2/24/2018"]
[FEN ""]

1. Nh3 Nh6 2. f4 d5 3. Nf2 Ng4 4. e3 Nxf2 5. Kxf2 c5 6. b3 Nc6 7. Bb5 Bd7 8. Bb2 a6 9. Bd3 Qc7 10. Nc3 e6 11. Qh5 Be7 12. Rhf1 Bf6 13. Kg1 Nb4 14. Rac1 Nxa2 15. Rce1 Nb4 16. f5 e5 17. e4 c4 18. Nxd5 Nxd5 19. Bxc4 Nb4 20. c3 Nc6 21. Qxf7+ Kd8 22. Ba3 Be8 23. Qd5+ Qd7 24. Bd6 Be7 25. Bxe7+ Kxe7 26. Qc5+ Qd6 27. Qb6 Bd7 28. d4 Nd8 29. Qa5 Nc6 30. Qa2 Kd8 31. Rd1 Kc7 32. Qf2 Rad8 33. b4 Rhf8 34. b5 axb5 35. Bxb5 g6 36. f6 Kb8 37. Bc4 Bc8 38. Bd5 Be6 39. Bxe6 Qxe6 40. d5 Qd6 41. Ra1 Kc7 42. dxc6 Qxc6 43. Ra5 Kb8 44. Qa7+

Does that prove that opening Nh3 is sound, or was it just a psychological play to take a slightly weaker player out of the book? Does it show that Carlsen is that much better because he can get away with such moves?

user15509: It does not prove that the opening is sound, but it does make a case for a successful practical opening. If your question is really "Should I try this myself?", the answer is "yes", because - especially under accelerated time controls - an element of surprise can be a huge factor.

user446: Let's remember that the late Tony Miles, at the 1980 European Championship, played 1... a6 as Black vs. Karpov's 1. e4, and won.
Single games mean nothing.

user12873: Carlsen is the strongest player in the world. He can get away with playing sub-par openings against average GMs because of the large difference in strength. Granted, Dreev is above your average GM, but still the gap in their playing levels is huge. 
1.Nh3 is one of the worst moves White can play, and Carlsen probably chose it for fun. The fact that Dreev answered with 1...Nh6 showed he wasn't taking the game that seriously either.

user19877: It was one game in online rapid. You cannot deduce from one game that 1.Nh3 is sound or not sound. Carlsen was actually MUCH worse out of the opening, and just outplayed Dreev later. It really means nothing other than Carlsen is currently much stronger.
Most likely 1.Nh3 is not good, and this is unusual for a first move: Stockfish already evals this as -.62 at a depth of 50.

20776: <p>In 2018, Magnus Carlsen played a <a href="https://www.chessgames.com/perl/chessgame?gid=1913200" rel="nofollow noreferrer">rapid game on chess.com</a> against Grandmaster Aleksey Dreev in which his opening move was 1. Nh3.</p>
<pre><code>[Title &quot;Magnus Carlsen-Alexey Dreev, Pro Chess League, chess.com INT, 2/24/2018&quot;]
[FEN &quot;&quot;]

1. Nh3 Nh6 2. f4 d5 3. Nf2 Ng4 4. e3 Nxf2 5. Kxf2 c5 6. b3 Nc6 7. Bb5 Bd7 8. Bb2 a6 9. Bd3 Qc7 10. Nc3 e6 11. Qh5 Be7 12. Rhf1 Bf6 13. Kg1 Nb4 14. Rac1 Nxa2 15. Rce1 Nb4 16. f5 e5 17. e4 c4 18. Nxd5 Nxd5 19. Bxc4 Nb4 20. c3 Nc6 21. Qxf7+ Kd8 22. Ba3 Be8 23. Qd5+ Qd7 24. Bd6 Be7 25. Bxe7+ Kxe7 26. Qc5+ Qd6 27. Qb6 Bd7 28. d4 Nd8 29. Qa5 Nc6 30. Qa2 Kd8 31. Rd1 Kc7 32. Qf2 Rad8 33. b4 Rhf8 34. b5 axb5 35. Bxb5 g6 36. f6 Kb8 37. Bc4 Bc8 38. Bd5 Be6 39. Bxe6 Qxe6 40. d5 Qd6 41. Ra1 Kc7 42. dxc6 Qxc6 43. Ra5 Kb8 44. Qa7+
</code></pre>
<p>Does that prove that opening Nh3 is sound, or was it just a psychological play to take a slightly weaker player out of the book? Does it show that Carlsen is that much better because he can get away with such moves?</p>
 15509: <p>It does not prove that the opening is sound, but it does make a case for a successful practical opening. If your question is really "Should I try this myself?", the answer is "yes", because - especially under accelerated time controls - an element of surprise can be a huge factor.</p>
 446: <p>Let's remember that the late Tony Miles, at the 1980 European Championship, played 1... a6 as Black vs. Karpov's 1. e4, and won.</p>

<p>Single games mean nothing.</p>
 12873: <p>Carlsen is the strongest player in the world. He can get away with playing sub-par openings against average GMs because of the large difference in strength. Granted, Dreev is above your average GM, but still the gap in their playing levels is huge. </p>

<p>1.Nh3 is one of the worst moves White can play, and Carlsen probably chose it for fun. The fact that Dreev answered with 1...Nh6 showed he wasn't taking the game that seriously either.</p>
 19877: <p>It was one game in online rapid. You cannot deduce from one game that 1.Nh3 is sound or not sound. Carlsen was actually MUCH worse out of the opening, and just outplayed Dreev later. It really means nothing other than Carlsen is currently much stronger.</p>

<p>Most likely 1.Nh3 is not good, and this is unusual for a first move: Stockfish already evals this as -.62 at a depth of 50.</p>
